Hundreds of refugees who had been living in the Dunkirk refugee camp are said to be unaccounted for, including several groups of unaccompanied minors, after a fire ravaged the encampment in northern France.

Charities have warned that while most refugees in the camp are now in three local gymnasiums under the orders of the local authority, several hundred have left the Dunkirk area and are thought to have made their way to Calais.

As many as 1,600 refugees were in the camp when the blaze broke out on Monday evening, according to Grande-Synthe Mayor Damien Carême and prefect Michel Lalande, the top government official for the region. Three mobile police units were deployed in the area to head off tensions prompted by the camp’s demise, the government said in a statement.

Mr Lalande said about 1,500 people, including hundreds of children, had to be evacuated, and that while up to 300 people had already been taken to makeshift shelters, others had simply run away.

Volunteers told The Independent on Tuesday that several hundred people were walking on foot to Calais from the Dunkirk site, among them groups of children.

Annie Gavrilescu from charity Help Refugees told The Independent: “There are a few hundred refugees somewhere between Calais and Dunkirk, with a few groups of mainly kids, making their way to Calais after what happened. We don’t know exactly how many. We’re trying to find these people and offer them food and blankets.

“For hours after the fire broke out it seemed the authorities just didn’t know what to do, and then they opened three gymnasiums that are not being used at the moment – but that’s not a permanent solution and it isn’t clear how long people will be allowed to remain there.

“The camp was meant to stay open until September, but now there appear to be no plans to rebuild. We really don’t know what’s on the cards. The local authority must provide long term solutions for those who lost everything in the fire, as the initial tensions themselves seemed to be about a shortage of accommodation available in the camp.

“We’ve set up an emergency fund to help them respond to the situation as quickly and effectively as possible, but the French authorities need to create an appropriate solution for these people. It’s now more urgent than ever.”

Ms Gavrilescu added that unaccompanied minors who were living in the camp are a primary concern, particularly as some already appear to be going off the radar. While local authorities have said there are only about 10 unaccompanied minors, charities have put the number at more than 100.

“The unaccompanied minors are a particular concern,” she said. “We have received some reports that some lone children are being turned away from the family gymnasium, and faced with the choice of either staying with adult men or wander the streets. Some are making their way to Calais, where nothing is available to them.

“The children with family in the UK shouldn’t have been in the camp anyway. They have documented family links, but because the family reunification process isn’t working, they ended up in the camp and stayed there for much too long.”

Michael McHugh, from the Refugee Youth Service, said it was concerning that there was no accommodation designated for unaccompanied minors, and that children were subsequently sharing small spaces with potentially dangerous adults.

“There’s no separate accommodation for minors. One gymnasium is mainly families, another majority Kurds and another that is Afghans. But they don’t seem to have any age-appropriate for unaccompanied minors. Housing unaccompanied minors in gymnasiums with adults, without safeguarding in place is not ideal and is not good practice,” he told The Independent.

“We’re now in a situation where individuals who have potentially been involved in this violence are in the same space as people who are victims of it.

Fire ravages Dunkirk refugee camp in northern France

“One unaccompanied minor was turned away from a centre because he was told he was not with a family and it was for families only. There is a real lack of child-focused response to this. Because the lone children are incredibly vulnerable, and this is a crisis within a crisis and people tend to wander off.

“What is the plan? Are we to move children back into the gymnasium for a few days only to put them back into a camp, even though 80 per cent of them do have family in the UK that we’re aware of?​”

Last month the French authorities said the camp would be dismantled because of growing violence between those living there. Police were regularly being called to deal with occupants of the camp trying to stop traffic on the main road nearby so they could board lorries on their way to the UK.

Charities are now liaising with French authorities to ensure unaccompanied children are offered safety, and calling on the UK Government to immediately transfer 80 children they had identified in the camp as having relatives in the UK and the legal right to be safely and legally transferred.

Safe Passage, which has been working in the camp in partnership with the Dunkirk Legal Centre and Help Refugees, has sent the list of 80 Dublin eligible children to the UK Home Office, and will be sharing that list with their French counterparts.

Currently no arrangements have been made by French or UK authorities for the safe accommodation of unaccompanied children from the Dunkirk camp, leaving the children at real risk of disappearing in the chaos, the charity said.

Rabbi Janet Darley, spokesperson for Safe Passage said: “The children Safe Passage are working with in Dunkirk should never have been in the camp in the first place; they have a moral and a legal right to be with their relatives in the UK.