The blaze broke out around 02:30 (01:30 GMT) at the Pulse club in Kocani, a town around 100km (60 miles) east of the capital, Skopje, where 1,500 people were attending a concert by DNK, a popular hip-hop duo in the country.

Prime Minister Hristijan Mickoski called it a “difficult and very sad day” for the country, which had lost many “young lives”.

Arrest warrants were issued for four people, interior minister Pance Toskovski said at the scene, without giving further details. He announced the arrest of a man earlier and state news agency Mia said the club owner was detained.

Citing initial reports, Toskovski said the fire had been started by sparks from pyrotechnic devices that had hit the ceiling, which was made of highly flammable material.

Footage shows the band playing on stage when two flares go off, after which sparks then catch fire on the ceiling before spreading rapidly.

Video verified by the BBC shows people trying to extinguish the flames on the ceiling. The footage shows the club was still full and some people appeared to be watching efforts to put out the fire rather than leaving.

Marija Taseva, 20, told Channel 5 TV she was caught in a crush at the club as people rushed for the exits. She recalled falling to the ground and being trampled during the chaos before managing to get out.

“I don’t know how, but somehow I managed to get out,” she told the Reuters news agency. “I’m fine now, but there are many dead.”

She added that her 25-year-old sister – who her family had previously been searching for – had died, saying: “I was saved and she wasn’t.”

Red Cross volunteer Mustafa Saidov said most of those affected were young people aged 18-20.

“The situation is brutal, chaotic, the stories are very sad, and unfortunately many young lives are lost,” he added.

North Macedonia’s interior minister Toskovski said in an earlier update that 35 of the deceased had been identified at the time.

Kocani’s hospital director said earlier that staff had been struggling to identify patients due to a lack of ID cards.

She said that those deceased were aged between 14 and 24. Eighteen patients are said to be in critical condition.

Local media has reported that the government is set to declare seven days of national mourning, and carry out urgent inspections of all nightclubs and restaurants used for hosting large gatherings.

Prime Minister Mickoski said the government was “fully mobilised and will do everything necessary to deal with the consequences and determine the causes of this tragedy”.

DNK was formed in 2002 and has topped the charts over the past decade.

European leaders have voiced their condolences, with European Commission President Ursula Von Der Leyen saying the EU “stands in solidarity with the people of North Macedonia in this difficult time”.

Neighbouring Serbian President Aleksandar Vucic called it “a tragedy of immense magnitude”, adding that fears remain as “many more people will not be able to withstand the level of injuries they have at this moment.

The blaze is said to have started around 03:00 (02:00 GMT) at the Pulse club in Kocani, a town around 100 km (60 miles) east of the capital, Skopje. Footage posted on social media shows the building engulfed in flames.

As many as 1,500 were said to have been attending a concert by the band DNK, a hip-hop duo popular in the country.

Interior Minister Pance Toskovski said that according to initial reports, the fire started from sparks caused by pyrotechnic devices.

He told reporters in front of the Kocani police station that sparks then hit the ceiling made of highly flammable material, before the fire spread through the club. He said some arrests had been made.

Footage shows the band playing on stage when two flares go off, sparks then catch on the ceiling before rapidly spreading.

Prime Minister Hristijan Mickoski wrote in a statement on Facebook that the government was “fully mobilised and will do everything necessary to deal with the consequences and determine the causes of this tragedy”

He called it “difficult and very sad day” for the country which has now lost “so many” young lives.

The hospital in Kocani initially reported 90 admissions, with many suffering severe burns. Some of the injured have since been transferred to hospitals in Skopje for further treatment.