Hundreds of migrants were evacuated late on Monday as a blaze swept through wooden shelters at a migrant camp in northern France, reducing it to "a heap of ashes," the regional chief said.

Officials said more than half of the Grande-Synthe camp was wrecked, and at least 10 people were injured.

Firefighters worked into the early hours of Tuesday to contain the blaze which left only around 70 of 300 huts intact.

"It will be impossible to put the huts back where they were before," Michel Lalande, prefect of France's Nord region, told reporters at the scene.

The senior local offical later confirmed that three gymnasiums had been put to use to provide shelter.

The fire broke out hours after a knife fight and scuffles between Afghan and Kurdish migrants forced riot police to intervene. At one stage, up to 150 migrants were involved in the clashes.

One of the injured migrants was knocked over by a car on a highway outside the camp and was in a critical condition, police said. Three other migrants had stab wounds. Police and local authorities were on Tuesday investigating the cause of the brawl.

Growing numbers

Grande-Synthe lies just outside the coastal town of Dunkirk and is home to some 1,500 migrants. The camp has swelled since the destruction last October of the squalid "Jungle" camp near Calais, about 40 kilometers (25 miles) away.

French officials had said in mid-March that security forces were planning to start dismantling the camp following clashes at the site.

Last week, migrants from Grande-Synthe had tried to block the nearby highway with tree trunks and branches in an attempt to stop the traffic and clamber onto trucks and cars in the hope of reaching Britain, across the Channel.

France's northern coast has been a magnet for refugees and migrants trying to reach the UK since the turn of the century, with French authorities repeatedly tearing down camps in the region.

Eyes on presidential election

With the first round of the French presidential electionless than two weeks away, Monday night's fire quickly became a campaign issue with with far-right leader Marine Le Pen claiming the blaze underlined the need to control immigration.

"This chaos must stop," she said. "All migrants' camps will be dismantled after my election if the French people elect me as head of state."

Le Pen's main rival in the presidential race, Emmanuel Macron, has pledged to scrap a treaty with the UK under which France has secured its northern border to stop migrants crossing the narrow English Channel.

"We will need to take up discussions with Britain again on the situation which leaves us acting as border guards for this country," Richard Ferrand, secretary general of Macron's party, told the LCI channel.

mm, ksb/jm (AFP, AP, Reuters)