France's human rights watchdog said on Wednesday the government bore responsibility for "inhuman" conditions that migrants face in the region of Calais where about 400 people have returned after a huge shanty camp was dismantled last year.
Earlier this month, two French charities accused police of using excessive force against migrants and preventing aid groups from distributing meals.
The human rights watchdog, an independent public body, said that its officials had interviewed migrants on Monday and found evidence of "unprecedented" rights violations.
"The rights defender demands that the violations of migrants' fundamental rights be ceased immediately," the watchdog said in a statement, accusing the government of allowing "inhuman living conditions."
Thousands of migrants fleeing war and poverty in the Middle East, Africa and Asia have converged on the port city over the past decade, hoping to find a way of getting across the Channel to Britain.
Most attempt to climb onto lorries or trains using the Channel Tunnel. Police have had to be deployed permanently in the area.
Despite the dismantling of the camp known as "the jungle" in November 2016, local authorities and associations have said around 400 to 600 hundreds of migrants including young children were still trying to get to Britain from Calais.
"The desire to get migrants to leave Calais has led to a situation where no shelters are tolerated. People — some of whom are minors — sleep on the ground regardless of the weather conditions," the rights watchdog read.
It also said migrants were deprived of sleep and denied access to water from the police.
"Women ... could be subject to rape and sexual exploitation. Many of them have babies with them and several are to give birth in the coming weeks," the watchdog said.
A spokesman with the local government had no immediate comment. Nobody was immediately available for comment at the French Interior Ministry.