The patients of a psychiatrist accused of prescribing massive doses of drugs to addicts at a private clinic were today urged not to panic about their treatment.

Dr Tom Onen, who is employed by Sussex Weald and Downs NHS Trust, is one of two psychiatrists facing a medical disciplinary hearing in London.

The General Medical Council's professional conduct committee has been told that Dr Onen, 52, and Dr Walter Onyango, 50, handed out daily prescriptions for methadone, pills and tablets at quantities of up to ten times the dose which would kill a non-addict.

The pair also prescribed a range of other drugs in "inappropriate" combinations and doses for addicts at the private Sunny Medical Centre in south-east London from 1995 to 1996, it is claimed.

Dr Onen has worked as a consultant adult NHS psychiatrist in the Crawley and Horsham area since 1993.

Trust chief executive Frances Russell said Dr Onen's private practice, with which the hearing is dealing, was completely separate from his NHS work.

She said: "We have carried out a clinical review and audit of his work for us and everything he has done has been correct and satisfactory.

"We are satisfied his NHS patients in the area have nothing to worry about."

The GMC hearing was told that one male patient later died of methadone intoxication and a woman patient died of bronchopneumonia and the ingestion of a tranquilliser and an opium derivative.

The two psychiatrists are accused of serious professional misconduct by "irresponsibly and inappropriately" prescribing drugs to 31 patients, in the case of Dr Onen, and to seven patients in the case of Dr Onyango. Both deny the allegations.

The hearing is expected to last five weeks.