French authorities are investigating at least six alleged attacks on refugees at the makeshift Calais Jungle migrant camp.
Volunteer legal teams have described the rise in attacks on migrants as 'endemic".
It is currently believed 5,000 refugees are living at the camp.
A Syrian man called Ahmed told the BBC he and his friends were badly beaten leaving him with a black eye and a broken jaw.
Another of his friends was kept under surveillance for four days after a bleed on the brain was discovered after a severe concussion.
Ahmed said the assault lasted 20 to 30 minutes.
The head of a legal centre at the camp, Marianne Humbersot, has said she has been told of 20 attacks in the last two weeks.
She has said many migrants do not want to notify the police.
The investigation into the attacks has not identified any individuals but regional prosecutor, Jean-Pierre Valensi, said they know the perpetrators drive a black BMW and use metal weapons.
