A service helping prevent deaths and inhumane treatment of people held in police custody in Lambeth is under threat, according to its chair.

Cuts to the Independent Custody Visit (ICV) service across London were made by the Metropolitan Police Authority (MPA) this month.

The volunteers – who make random visits to custody suites in the borough’s three main police stations at Streatham, Brixton and Kennington – can now only report its findings to the MPA four times a year.

Lambeth’s ICV panel chair, Jane Warwick, said the move will “neuter” the service’s effectiveness and is the latest in a string of attempts by the MPA to weaken and eventually remove the independent service.

Previously it was able to pass on its findings to the MPA – responsible for maintaining conditions in police cells and custody suites – monthly.

Mrs Warwick said: “It is vital the service is maintained, not diluted.”

She said the new arrangements will destroy the cohesion of the panel, corrode its influence, and leave newly appointed ICV visitors without the support of experienced visitors.

ICVs are intended to protect and defend the rights of vulnerable detainees, including those suffering from mental health issues, juveniles or detainees for the immigration authorities - who can legally at the be held for up to seven days.

The panel played a vital role following the death of Balham resident Sean Rigg at Brixton police station in 2008.

Lambeth police have promised to continue meeting it monthly to discuss more serious visit findings.

MPA has said the service is not under threat, and quarterly meetings were necessary because of a reduction in MPA officers dedicated to the ICV service.

In a letter to panel chairs, Clive Lawton, MPA community engagement and citizen focus sub-committee chair, said: "ICVs are still required to record and report all matters of concern following a visit and not leave such concerns to the next panel meeting. In short, nothing will change in how ICVs do what they do, according to best practice, in the practical 'sharp end' of their task. “