A GP accused of prescribing sleeping tablets to enable a pensioner to end her life was criticised by a General Medical Council expert yesterday.

Dr Leonard Peter told a GMC hearing that the standard of care provided by Dr Iain Kerr, from Glasgow, fell far below that expected of a general practitioner.

Dr Peter was called to give evidence by the GMC's counsel on the third day of the hearing which is considering Dr Kerr's fitness to practise medicine.

The panel has already been told Dr Kerr spoke in a staff appraisal about giving the sleeping tablets called sodium amytal to the elderly woman, known as Patient A, so she could end her life.

They have also heard the woman later went on to overdose using different drugs prescribed by Dr Kerr. In addition, the GP faces allegations of inappropriate conduct after prescribing sodium amytal to five other patients Dr Peter said yesterday: "It's really unacceptable for a doctor to prescribe a powerful, potentially lethal drug to a vulnerable elderly person if that doctor is aware they wish to end their life."

He also said it was an "extraordinary action" to prescribe sodium amytal to Patient A. The Committee on the Safety of Medicines has published guidance on the drug saying it should only be used to treat "severe and intractable insomnia".

An overdose of sodium amytal could cause irreparable brain damage, not death, according to Dr Peter.

"There's no guarantee that what you'll get is death - what you might get is terrible disability," he said.

Dr Peter also criticised Dr Kerr for prescribing Patient A with temazepam just days after she tried to kill herself using this medicine.

He said: "It's inexplicable in the context that three days earlier Patient A had attempted to end her life with an overdose of temazepam."

Patient A, who had osteoporosis and chronic lower back pain and feared becoming a burden on her family, killed herself using a combination of temazepam and two other drugs in December 2005.

The hearing was told that Dr Kerr wished to state "categorically" that it was not his intention to help Patient A end her life by prescribing her temazepam three days after she attempted suicide.

The woman had already disposed of the sodium amytal, prescribed in 1998, because she did not want Dr Kerr to get into trouble, according to evidence presented earlier this week. When cross-examined by Dr Kerr's defence lawyer Michael Mylones, Dr Peter admitted he was incorrect in asserting that Dr Kerr had broken the law.

He said he had mistakenly believed the Suicide Act 1961, which prohibits assisting suicide in England and Wales, applied to Scotland.

In Scotland there has not been any legislation on suicide. Those who assist another to commit or attempt suicide are usually charged with culpable homicide. Dr Kerr, 61, has a practice at the Williamwood Medical Centre, in Seres Road, Glasgow.

Rhonda Waters, his practice nurse, said in a written statement, submitted at the hearing: "She (Patient A) told me she had to see Dr Kerr so he could check her pills so he could see they were in date for when she wanted to die. I was really concerned when she told me this." The hearing continues today when Patient A's son is expected to give evidence by videolink.