Eurostar services at Gare du Nord were scrapped for the day, after the 500kg bomb was found on tracks in the Paris suburb of Saint-Denis during overnight work.

Homes with windows in a 500m (1,600ft) radius of the bomb were evacuated and part of the Paris circular périphérique was shut as the clearance operation took place.

French Transport Minister Philippe Tabarot said local rail services at Gare du Nord would not resume until late afternoon at the earliest.

Tabarot said on Friday morning that a bomb disposal team was on the scene and there was nothing to worry about. “If we get the green light from the police chief in the coming hours, part of the service could – and I mean could – start up again after 16:00 (15:00G),” he said.

Eurostar said it expected services to return to normal on Saturday.

The bomb was discovered 200m away from the busy Paris périphérique, about 2.5km (1.5 miles) north of Gare du Nord, Europe’s busiest train station.

A nearby short northern stretch of the ring road and the A1 motorway were shut around Porte de la Chapelle. Traffic jams were recorded on 218km of roads in the Paris region.

Authorities in Saint-Denis said there were six schools and a care facility for elderly people inside the evacuation zone, but they were not at risk, because they did not have windows overlooking the area.

Eurostar services were running normally between Brussels and Marne-la-Vallée to the east of Paris as well as trains between London and Brussels and London and Amsterdam.

High-speed TGV trains into Gare du Nord were also badly hit, although some services were diverted to Gare de Lyon in Paris.

The railyards around occupied Paris were regular targets for British and American bombers during World War Two, the BBC’s Hugh Schofield in Paris reports.

Eurostar said passengers would be able to exchange their tickets for free to travel at another date or time in the same class, subject to availability.

“Eurostar will run two additional trains [on Saturday]: a train leaving London for Paris in the morning, and a train leaving Paris for London in the afternoon,” it said in a statement.

Queues were beginning to form by 08:30 GMT at St Pancras train station in London as passengers tried to work out what they could do.

One group was approaching the front of the line after a two-and-a-half hour wait.

Their 07:00 GMT train was cancelled and they planned to travel to Lille and make a three-hour bus journey to Paris.

Jess Sayer from Norwich told the BBC on Friday morning that she was stuck in Paris with her husband and best friend after celebrating her 40th birthday on Thursday.

“We’re frantically on our phones trying to find out what to do,” she said, explaining they had not been able to book a train for Saturday via the website.

“We just tried to get a flight. All the flights are booked up so at the moment we are completely stuck in Paris with no way of getting home,” she said. “Do we get a hotel and risk trying to get the Eurostar home tomorrow? Or look into ferries?”

Her friend, Sarah Fitzgerald, said she was trying to get back to London to help her family prepare for a funeral on Monday.

The Paris cancellations coincided with the middle of Paris Fashion Week and meant that personal shopper Anna Griffiths was unable to travel to Paris for a function.

“We work with all of the designer brands, and Chloé Fashion House had invited me to Paris for their show and a showroom event and a big dinner tonight.”

Ivana Koralek told the BBC she had decided to cancel a trip to see her elderly mother and nephew in France.

She said she had been unable to rebook for three weeks’ time because ticket machines in the station did not offer the discount she had originally received.

Karen Hamblin, from Chester, had travelled to London on Thursday evening to catch a Friday train to Paris for a three-day getaway to celebrate her husband’s birthday.

She said she was told at about 07:00 that their train was cancelled.

“As we were effectively stranded, we have decided to transfer our ticket and travel to Lille,” she said. “Lunch in Lille and [we’ll] then work out how to get to Paris from there!”

Sir Keir Starmer, who is expected to attend the summit in Paris, said it was a “once-in-a-generation moment for our national security” and it was clear Europe must take a greater role in Nato.

It comes after Donald Trump’s special envoy to Ukraine said European leaders would be consulted but not take part in any talks between US and Russia over ending the war.

Senior White House figures, including US Secretary of State Marco Rubio, are due to meet Russian negotiators in Saudi Arabia in the coming days. US officials said that Ukraine was also invited – although President Volodymyr Zelensky says his country has received no such invitation.

In remarks likely to raise concern in Ukraine and among European allies, special envoy Keith Kellogg said previous negotiations had failed because too many parties had been involved.

“It may be like chalk on the blackboard, it may grate a little bit, but I am telling you something that is really quite honest,” he said on Saturday.

Europe remains haunted by the Minsk agreements, a failed ceasefire deal between Ukraine and Russia reached in 2015. The talks, which were brokered by France and Germany, sought to end fighting in the Donbas region of eastern Ukraine.

Sir Keir is understood to see his role as bringing US and Europe together to ensure a united approach to peace in Ukraine.

The UK prime minister will discuss the views of European leaders when he visits US President Trump at the White House at the end of this month.

A further meeting of European leaders together with Zelensky is expected after Sir Keir returns from Washington.

Sir Keir said the UK would “work to ensure we keep the US and Europe together”, adding the two could not “allow any divisions in the alliance to distract” from “external enemies”.

“This is a once in a generation moment for our national security where we engage with the reality of the world today and the threat we face from Russia,” he said.

“It’s clear Europe must take on a greater role in Nato as we work with the United States to secure Ukraine’s future and face down the threat we face from Russia.”

Polish foreign minister Radoslaw Sikorski said Emmanuel Macron had called the summit of European leaders, which has not yet been announced by the French president.

Sikorski said: “President Trump has a method of operating, which the Russians call reconnaissance through battle. You push and you see what happens, and then you change your position, legitimate tactics. And we need to respond.”

Earlier on Saturday, Zelensky called for the creation of an “army of Europe” amid rising concern the US may no longer come to the continent’s aid.

Speaking at the Munich Security Conference, he said US Vice-President JD Vance’s speech at the event had made it clear that the old relationship between Europe and America was “ending” and the continent “needs to adjust to that”.

But Zelensky also said Ukraine would “never accept deals made behind our backs without our involvement” after Trump and Russian President Vladimir Putin agreed to start peace talks.

Earlier this week the US president announced he had a lengthy phone conversation with the Russian leader and that negotiations to stop the “ridiculous war” in Ukraine would begin “immediately”.

Trump then “informed” Zelensky of his plan.

Trump appeared confident that his leadership style could pave the way for a peace deal in Ukraine.

His rapprochement with Putin brought to an end more than three years of silence between Moscow and Washington.

Trump’s shock announcement rekindled memories of his meeting with Putin in Helsinki back in 2018.

The two men held nearly two hours of closed-door talks in the Finnish capital and went on to deliver a joint news conference, where Trump defended Russia over claims of interference in the 2016 US presidential election.

His comments came despite US intelligence agencies concluding, in 2016, that Russia was behind an effort to tip the scale of the US election against Hillary Clinton, with a state-authorised campaign of cyber attacks and fake news stories planted on social media.

On Saturday, US Secretary of State Marco Rubio also held a phone call with Russia’s foreign minister “building on” the 12 February call between Trump and Putin.

Senior officials from the Trump administration will start peace talks with Russian and Ukrainian negotiators in Saudi Arabia in the coming days, US Representative Michael McCaul told Reuters news agency.

McCaul, chairman of the House Foreign Affairs Committee, said he understood Zelensky had been invited to take part in the Saudi talks, which were aimed at arranging a meeting with Trump, Putin and the Ukrainian president “to finally bring peace and end this conflict”.

A day earlier, Vance had launched a scalding attack on European democracies, saying the greatest threat facing the continent was not from Russia and China, but “from within”.

In a speech at the Munich Security Conference, he repeated the Trump administration’s line that Europe must “step up in a big way to provide for its own defence”.

David Lammy has said the UK and EU countries must spend more on defence, with Europe facing an “existential question” even in the event of a negotiated peace in Ukraine.

The UK foreign secretary told the Munich Security Conference on Saturday “Putin will not go away”, and that, while it was positive 23 Nato countries were now spending at least 2% of their GDP on defence, “we all know we have to go upward”.

On Monday, against the sumptuous backdrop of the city’s 125-year-old Grand Palais, representatives from 80 countries including world leaders, tech bosses, academics and other experts, will gather for a two-day global summit to discuss current progress, and future goals, for the rapidly-evolving, hugely-disruptive technology that is artificial intelligence.

That might be what’s on the official agenda of the Artificial Intelligence Action Summit, but there is something else that’s breathing fire into this particular talking shop: DeepSeek.

A horse racing fan once told me that the night before a big race, everyone’s a winner.

And with China dramatically blowing the AI competition in a new direction with DeepSeek, its super-efficient and super-viral AI assistant, suddenly there’s a feeling ahead of the summit that the pole position occupied by the US AI sector, despite its vast wealth and AI infrastructure, might not be quite so out-of-reach after all.

Prof Gina Neff, from the Minderoo Centre for Technology and Democracy at the University of Cambridge, says there is currently “a vacuum for global leadership on AI”.

Prof Dame Wendy Hall, from Southampton University, agrees. “DeepSeek made everybody realise that China is a force to be reckoned with,” says the computer scientist.

“We don’t have to just go along with what the big companies on the West Coast are saying. We need global dialogue.”

On that front, the timing of the summit could not be better.

Europe also spies an opportunity to make a new bid for the AI crown. One of French President Emmanuel Macron’s officials described the summit to journalists as a “wake up call” for France and Europe, adding that the bloc must not let the AI revolution “pass it by”.

Other countries also recognise a potential shifting of AI power in the air. India PM Narendra Modi has confirmed his attendance at this summit – having not come to previous gatherings.

The US is sending some serious firepower as a defensive signal of its own, including Vice President JD Vance, OpenAI CEO Sam Altman, and Google’s Sundar Pichai.

Elon Musk is notably absent from the official guest list, but he will undoubtedly have something to say about it all, whether he’s there in person or not.

British Prime Minister Kier Starmer is also reportedly staying away.

There have been two previous summits, the first held in the UK and the second in South Korea. A lot has happened since the AI world gathered for the first time, on the steps of the historic mansion of Bletchley House, in November 2023, and promised to try to maximise the benefits of AI while minimising the risks. For one thing, half of the global population has been to the polls since then.

In Bletchley Park, China’s Vice Minister for Science and Technology, Wu Zhaohui attended. But there were whispers that he was kept at arms length, on the grounds of national security.

In Paris, by comparison I expect China to be guests of honour. The country is reportedly sending one of its most senior leaders, Ding Xuexiang, a close ally of President Xi JinPing. There’s also a buzz around whether DeepSeek creator Liang Wenfeng will join him.

I asked ChatGPT to list some of AI’s notable milestones since the South Korea summit of May 2024. DeepSeek did not make the cut.

Of course there is much more to AI than generative AI like both DeepSeek and ChatGPT – tools that create content like text, images, video. It may well be the most widely accessible to us as consumers. But there are also AI tools that spot disease symptoms, model climate change solutions, develop new formulas for drugs – and that will all be in scope in Paris.

Furthermore, the David v Goliath narrative around which the story of DeepSeek hangs does merit further scrutiny. The boss of AI firm Anthropic, Dario Amodei, has written a compelling blog about whether DeepSeek really was built at a fraction of the cost of its US rivals.

We do know that it was built on their shoulders: using a number of Nvidia chips (probably older ones, because of US sanctions) and some opensource AI architecture developed by Meta. In addition, OpenAI has complained that rivals are using its work in order to advance their own (contacts in the creative industries was amused at the irony of this, given that OpenAI products will happily produce output “in the style of” individual human creators).

But nonetheless DeepSeek succeeded in shaking up the AI sector in a way not even AI itself might have predicted. And it wiped a lot of money off the value of some of the biggest players in the process. It will almost certainly be a huge topic of conversation all around those Parisian conference rooms.

There’s one more theme running through the AI Summit that will be worth keeping an eye on.

The first summit had the word “safety” in its title. Some felt the event pushed the narrative too hard and terrified people with dark talk of existential threats.

But it hasn’t fallen of the agenda entirely.

As a subject, AI safety is a rather broad church. It can relate to any number of risks: the generation and spread of misinformation, displays of bias and discrimination against individuals or races, the ongoing development by multiple countries of AI-controlled weapons, the potential for AI to create unstoppable computer viruses.

Prof Geoffrey Hinton, often described as one of the Godfathers of AI, says these as “short-term risks”. They might be up for discussion in Paris, but he argued on BBC Radio 4’s Today programme last week that they are unlikely to garner strong international collaboration in the long term.

The big scenario which he believes will really pull everyone together is the prospect of AI becoming more intelligent than humans – and wanting to seize control.

“Nobody wants AI to take over from people,” he says. “The Chinese would much rather the Chinese Communist Party ran the show than AI.”

Prof Hinton compared this eventuality to the height of the Cold War, when the US and Russia “just about succeeded” in collaborating in order to prevent global nuclear war.

“There’s no hope of stopping [AI development],” he said. “What we’ve got to do is to try to develop it safely.”

Prof Max Tegmark, founder of the Future of Life Institute, also share a stark warning. “Either we develop amazing AI that helps humans, or uncontrollable AI that replaces humans,” he says.

“We are unfortunately closer to building AI than to figuring out how to control it.”

Prof Tegmark hopes the summit will push for binding safety standards “like we have in every other critical industry”.

The ad was meant to promote the resumption of Pakistan International Airlines’ flights to the French capital and had the caption “Paris, we’re coming today”.

Some social media users noted the ad’s resemblance to the terrorist attacks in the US on 11 September 2001.

“Is this an advertisement or a threat?” one user wrote on X. Another called for the company to “fire your marketing manager”.

The image has been viewed more than 21 million times on X since it was published last week and has drawn swift backlash.

Prime Minister Shehbaz Sharif has ordered an investigation into the matter, while Deputy Prime Minister Ishaq Dar has also criticised the ad, Pakistan’s Geo News reported.

The 9/11 attacks saw hijackers crash passenger jets into the twin towers of the World Trade Center in New York and the Pentagon in Washington DC, killing nearly 3,000 people.

The alleged mastermind of the attacks, Khalid Sheikh Mohammad, was arrested in Pakistan in 2003.

Osama bin Laden, the leader of the al-Qaeda extremist network which planned the attacks, was killed by US troops in Pakistan in 2011.

Pakistani journalist Omar Quraishi said PIA’s ad left him “truly speechless”.

“Did the airline management not vet this?

“Do they not know about the 9/11 tragedy – which used planes to attack buildings? Did they not think that this would be perceived in similar fashion,” he wrote on X.

The airline has not commented on the incident.

The PIA, however, is no stranger to controversy.

Some X users pointed out that in 1979, the airline published an advertisement showing a passenger jet’s shadow over the twin towers.

In 2017, the airline was mocked after staff sacrificed a goat to ward off bad luck following one of the country’s worst air disasters.

And in 2019, PIA caused a stir when it told flight attendants to slim down or get grounded. Staff were told they had had six months to shed “excess weight”.

Ms Dali, whose identity was confirmed by CBS, boarded a Delta Airlines flight last week from New York’s JFK airport to Charles de Gaulle Airport in Paris without a boarding pass.

She was taken into custody upon arrival in France.

French National Police said the woman is of Russian nationality and was refused entry to France because she had no visa. She has not been charged.

Ms Dali was able to get through an advanced imaging technology body scanner at JFK airport, and dodge document and ID checks during the security process.

In a statement provided to CBS, a TSA spokesperson confirmed that “an individual without a boarding pass was physically screened without any prohibited items. The individual bypassed two identity verification and boarding status stations and boarded the aircraft.”

But it remains unclear how she was able to get through and board the plane.

“Nothing is of greater importance than matters of safety and security,” Delta said in a statement. “That’s why Delta is conducting an exhaustive investigation of what may have occurred and will work collaboratively with other aviation stakeholders and law enforcement to that end.”

The Guardian reported that once on board, Ms Dali moved from one bathroom to another and never took a seat – until flight attendants began to notice.

A social media video posted by a passenger shows the moment a captain explained to the plane that officials were coming to remove the woman.

“Folks, this is the captain, we are just waiting for the police to come on board,” he said in the video. “They may be here now and they directed us to keep everyone on the airplane until we sort out the extra passenger that’s on the plane.

“A man on the flight shared mobile phone video with CNN of the woman, who remains in France, allegedly making a disturbance on another flight that was set to return her to New York.

He said she repeated: “I do not want to go back to the USA. Only a judge can make me go back to the USA”.