French prosecutors are investigating at least six attacks on migrants at the makeshift Calais camp called the Jungle, reports the BBC.
Assaults on people living there are increasing, volunteer legal teams have claimed, and they described the situation as "endemic".
One Syrian, called Ahmed, told the BBC he and his friends had been severely beaten one night and taken to hospital.
About 5,000 migrants trying to reach the UK are thought to live at the camp.
Ahmed suffered a broken jaw and a black eye. One of his friends suffered a severe concussion, and was under medical supervision for four days because of a bleed on the brain.
The men say the attack on them lasted about 20 to 30 minutes.