A huge fire tore through at least half of the Grande-Synthe migrant camp outside the northern French city of Dunkirk on Monday night, an AFP correspondent reported.
Firefighters said at least ten people had been injured in the blaze, which witnesses said broke out after a row between migrants.
The camp was home to some 1,500 people by the end of March, living in closely-packed wooden huts.
Local officials said the blaze had affected around 20 of the huts, each of which accommodates four people, as firefighters continued to battle the flames.
A massive plume of smoke rose from the camp into the night sky and was visible from several kilometres away.
French officials had said in mid-March that security forces were planning to start dismantling the camp following clashes at the site.
The population of the Grande-Synthe camp has swelled since the destruction last October of the squalid "Jungle" camp near Calais, about 40 kilometres (25 miles) away.
For more than a decade France's northern coast has been a magnet for refugees and migrants trying to reach Britain, with French authorities repeatedly tearing down camps in the region.
Migrants gather along the northern coast in France seeking to break into trucks heading to Britain or pay smugglers to help them get across the Channel.
There have been several violent incidents at the Grande-Synthe camp, with police intervening last month after five men were injured in a fight. Another man was stabbed in November.
© 2017 AFP