Violent disturbances at Oxfordshire's Campsfield immigration detention centre were probably sparked by alleged assaults detailed in a new report, say campaigners.

A dossier detailing nearly 300 alleged assaults on detainees in detention across the UK has been handed to Government officials - and campaigners claim six of them happened at Campsfield House, near Kidlington.

A spokesman for the UK Borders Agency said officials would review the information and pass it to the police if necessary.

The Outsourcing Abuse report, released on, was compiled by law firm Birnberg Peirce & Partners and campaigning organisations Medical Justice and the National Coalition of Anti-Deportation Campaigns (NCADC).

The allegations were gathered from information given to campaigners by solicitors, alleged victims, visitors, medical staff and journalists.

But the report said the assaults, dating back to January 2004, could be difficult to prove and in many cases there were no independent witnesses.

It said: "This dossier provides evidence of widespread and seemingly systemic abuse of one of the most vulnerable communities of people in our society, who have fled their own countries seeking safety and refuge."

NCADC spokesman Emma Ginn said: "We have passed 48 highlighted cases to the Home Office with the demand that they are investigated or reinvestigated.

Teresa Hayter, of the Campaign to Close Campsfield, said: "This is probably the tip of the iceberg.

"In nearly every case the protests at Campsfield have been triggered by violent removals of people."

Campsfield, which holds 215 male asylum seekers, was opened in 1993 and is run by private firm GEO.

It has been hit by several violent disturbances over the past two years, including one last month when seven detainees escaped. Three are still on the run.

In August 2007, 26 detainees broke out after another disturbance. In March last year, riot police were called to restore order after a fire.

A UKBA spokesman said: "We have been asking for this information for at least nine months. We will review it and where necessary will refer it to the police."

No one at GEO was available to comment.