LILLE, France Two French charities accused police on Thursday of using excessive force against migrants and preventing aid groups from distributing meals in Calais, where about 400 people have returned following the dismantling of a camp last year.
Regional police chief Fabien Sudry said security services had respected the law.
"In a country with the rule of law, all people can file a legal complaint and ask for an investigation from the police inspector general. No legal complaints have been filed at this stage regarding police violence on migrants," he told Reuters.
Migrants fleeing poverty and war in the Middle East, Asia and Africa go to Calais hoping to cross the short stretch of sea to Britain by trying to leap on trucks and trains, or even walk through the tunnel under the Channel.
Hundreds of migrants and refugees have been returning to the port city despite the dismantling of the "jungle" camp that housed thousands of people late last year.
Dozens of police are still deployed permanently in the area where the camp once stood.
"These last few days, in the mornings, security forces have been coming to remove the migrants," Lucie Favry, from local aid association Utopia 56, told a news conference.
"They gas their sleeping bags to make them unusable and they gas or put holes in water canteens," she said.
The association said it had gathered witness accounts from mainly Eritrean migrants, who said they had been intimidated, beaten with truncheons or punched in the face.
In March, the mayor of Calais signed a decree banning gatherings that could stop aid groups distributing meals on the grounds that it was causing a rise in ethnic tensions and conflict between rival groups of migrants.
Francois Guennoc, a spokesman for local charity Auberge des Migrants, said police officers were now actively preventing volunteers from distributing food and water.
"Everyday we are seeing manhunts, illegal police violence, harassment of refugees and the prevention of the distribution of water and meals," Guennoc said.
(Reporting by Pierre Savary; Writing by John Irish; Editing by Andrew Bolton)