Detainees at a Kidlington immigration detention centre will be given more rights to complain about mistreatment after Home Office inspectors found the system was open to abuse.

The Border and Immigration Agency Complaints Audit Committee said procedures used for the UK's network of privately-run removal centres, including Campsfield House were inadequate.

The committee's annual report 2006/7 said: "We regret that we are able to give only the most limited assurance on the quality and integrity of complaints management information which we have audited.

"We have become increasingly concerned at the weaknesses of systems and procedures for recording, tracking and managing formal complaints."

The report found only 29 per cent of cases alleging misconduct by named officials and contract staff were handled within time targets.

Border and Immigration Agency investigations were "poor" and only eight per cent of complainants were interviewed.

Changes to the process in 2006 had led to a number of alleged assaults on detainees being categorised as "service delivery" complaints.

The report said this raised the risk that alleged misuse of force was "neither properly investigated nor appropriately challenged".

In response, Lin Homer, Chief Executive of the Border and Immigration Agency, said: "Since 2006 the Border and Immigration Agency has been actively working to design a radical, new complaints system which will come on line from February 2008.

"Changes were made last year to the handling of complaints in the detention estate."

A Home Office spokesman said the new procedures would include a guarantee that complainants would be able to speak to immigration officials about any allegations of misconduct.