French police have been accused of "unprovoked and extreme" violence against refugees, including children, in the port of Calais.

Refugees have been beaten badly enough to have limbs broken, attacked by police dogs and had their property destroyed, according to a new report by the Refugee Rights Data Project (RRDP).

A 16-year-old boy from Eritrea, found with swollen lips and loose teeth, told researchers of how he was attacked when he tried to hide in a lorry.

"When I tried to get on a truck, the police found me and started punching me in the face... I haven't received any care from anyone since then," he said.

Another teenager, a 17-year old boy from South Sudan, added: "The police beat me with a baton, which gave me cuts across the hands and chipped my front tooth. They also sprayed tear gas into my eyes".

A third told of how he witnessed a baton attack on a 16-year-old Eritrean so severe he thought the victim was dead, while a 35-year-old man found with his arm in a cast revealed how police broke his bones while walking to a food distribution point.

The report comes a year after the notorious Calais Jungle camp was demolished by French authorities in an attempt to disperse those refugees and migrants trying to reach the UK. An estimated 700 displaced people remain in the area.

Just over half of the 233 refugees surveyed by the RRDP – including 94 children aged as young as 12 – said they had been physically abused by police.

The charity said the violence level was even higher than when the Calais Jungle was in operation, with 88% now describing their treatment by police as "bad" or "very bad".

Numerous reports of "unprovoked" beatings were joined by complaints that officers were guilty of more unconventional methods of intimidation.

This included what the RRDP said amounted to a campaign of "intentional sleep deprivation" by uprooting refugees nightly and soaking their sleeping bags with tear gas to make them unusable.

The police are also accused of using plain-clothes officers to provoke refugees and take their shoes, so they would have to walk barefoot in the wet and cold.

One 17-year-old Eritrean girl told of how she was detained by police, driven to a remote location and abandoned. She said she was forced to walk three hours back to Calais in the night without knowing where she was.

Allegations of abuse in detention centres also emerged, with some complaining of being beaten, deprived of food and water, and even forced to go to the toilet on the floor in the holding cells.

Maddie Harris, who led the research, said the violence was "constant", with many refugees falling victim to "unprovoked extreme" violence by police multiple times.

"Officers, particularly the riot police appear to have no issue subjecting vulnerable migrants and asylum seekers, including unaccompanied children, to repeated exposure to tear gas, beatings and repeated destruction and confiscation of possessions such as sleeping bags, blankets, phones and shoes," she told The Independent.

"When giving testimony, most migrant and asylum seekers talk of multiple incidents where they have been the victim of unprovoked extreme violence at the hands of the police. One particular unaccompanied minor, when talking of an incident where he was beaten by the police, told me he had been gassed on three separate occasions in one day.

"I have personally witnessed numerous evictions and confiscations of possessions, unprovoked beatings, violent arrests and use of tear gas. I have also seen the physical results of these actions, from young boys walking in the rain with no shoes, to the physical scars on the faces of unaccompanied minors.

"The officers in question act with complete impunity and show no signs of adhering to their code of conduct."

Monday's (30 October) report comes a week after a government-commissioned study concluded it was "plausible" that excessive force, notably with tear gas, had been used against refugees.

However, it also said there is no evidence "to link the injuries reported by some migrants with law enforcement action".

The RRDP has urged the French authorities to "provide more humane standards on French soil" and wants Britain to offer protection to those children eligible to come to the UK.