Sir Keir Starmer has held a call with leaders from the EU, Turkey, Norway, Iceland and Canada as part of the ongoing diplomatic push on Ukraine.
During the meeting, the non-EU countries were briefed on the EU’s plans to step up defence, which include freeing up €800bn (£670bn) for military spending.
European Commission President Ursula von der Leyen said the move would help Europe protect “our people, territories and assets” and help “the long-term security of our brave neighbour Ukraine”.
UK Defence Secretary John Healey earlier returned from Washington DC, where he met with his US counterpart Pete Hegseth to discuss ending Russia’s war on Ukraine.
Addressing Hegseth, he said: “You challenged us to step up on Ukraine, on defence spending, on European security – and I say to you that we have we are and we will further.”
Hegseth said UK leadership was “critical” adding that “European leadership of Nato, led by the UK and others is we believe the future of defence on the continent”.
The US has paused military aid to Ukraine and stop sharing intelligence as it reviews “all aspects of this relationship”.
In a televised speech, French President Emmanuel Macron said “I want to believe the US will stay at our side, but we must be ready if that is not the case.”
The UK and France have said they are willing to provide peacekeeping troops to Ukraine and are urging other European countries to join what they have called a “coalition of the willing”.
According to UK officials about 20 countries are interested in joining the coalition, although would not necessarily offer to send troops, but instead provide other support.
But Sir Keir has said that in order to be effective their presence in Ukraine must be backed by security guarantees from the US.
US President Donald Trump has so far avoided committing to such support, instead arguing that the presence of American workers in Ukraine as part of a potential minerals deal, would be sufficient to deter Russia from further invading Ukraine.
Russia has flatly rejected such a move saying it would amount to “direct, official and unveiled involvement of Nato members in the war against Russia”.
Talks between the US and Ukraine aimed at reaching an agreement will take place next week in Saudi Arabia.
Speaking in Washington, Healey said: “It’s a lasting, secure peace that we all want to see. We’ve got a big role to play in Europe and we are determined to do that.”
Hegseth dismissed as “garbage” suggestions that under Trump’s leadership the US was becoming “pro-Russia”.
He said the president was “working with both sides in a way that only President Trump can”.
Progress towards an agreement appeared to take a step back after Trump and Zelensky had a dramatic row in front of cameras in the Oval Office.
However, Hegseth said the US president was “very encouraged by the signs we’re seeing” from Ukraine.
On Thursday the UK’s Ministry of Defence signed a £30m deal with an Anglo-American firm to provide Ukraine with Altius 600m and Altius 700m systems, designed to monitor an area before striking incoming targets.
Chancellor Rachel Reeves also announced a £2.26bn loan to Ukraine, funded by the profits generated from frozen Russian assets.
On Friday, Ukrainian Prime Minister Denys Shmyhal confirmed they had received the first tranche of the loan, amounting to £752m.
In a social media post, he said: “I am grateful to Keir Starmer, the UK government and our G7 partners for the mechanism to make Russian money work for Ukraine.
“We expect all sovereign assets of the Russian federation to be confiscated and transferred to benefit our country in the future.”
Earlier this week, Liberal Democrat leader Sir Ed Davey urged the prime minister to seize the frozen Russian assets held in the UK.
Sir Keir replied there were “ongoing discussions” but that the situation was “complicated”.
The Liberal Democrats are now calling on the attorney general to publish the legal advice on taking the assets.
The party’s shadow attorney general Ben Maguire said: “We need the chance to properly scrutinise the decision-making on this crucial issue, so the UK can then make the right choice for Ukraine.”