The controversial paediatrician David Southall accused a grieving mother of drugging and murdering her 10-year-old son, a disciplinary panel heard today.

Professor Southall, who was found guilty of serious professional misconduct two years ago for publicly accusing a father of murdering his sons, is charged with abusing his professional position and acting inappropriately when interviewing the mother, identified only as Mrs M, about the death of her eldest son, identified as M1, in June 1996.

The paediatrician is alleged to have made the accusation after being instructed to prepare a report by a local authority into the care proceedings relating to the woman's younger son, M2.

Prof Southall is accused of behaving in a way that was "inappropriate, added to the distress of a bereaved person", and was "an abuse" of his professional position.

He was suspended in 2004 by the General Medical Council from carrying out any child protection work for three years after accusing the solicitor Steve Clark of murdering two of his sons.

The GMC fitness to practise panel was told today by Richard Tyson QC, acting for the complainants, that an inquest into the death of the 10-year-old had ruled an open verdict over whether the death was suicide or an accident.

Mr Tyson said: "Catastrophically for the family, on June 3 1996, child M1, then only 10 years old, was found dead hanging from a belt from a curtain pole in the family home. How and why M1 died became an important feature later when Prof Southall became involved in this case."

Prof Southall also faces allegations of not acting in the best interests of several children when he transferred medical records from the Royal Brompton hospital in London to his new job at the North Staffordshire hospital in Stoke-on-Trent.

The disciplinary hearing heard accusations that the professor kept secret files on four children, identified only as A, B, D and H, and tampered with their medical records.

The paediatrician gained notoriety over his work at the North Staffordshire and the Royal Brompton hospitals, where he pioneered covert surveillance of parents suspected of abuse. He was also a strong advocate of the theory of Munchausen's syndrome by proxy, now known as fabricated illness, whereby caregivers fake or induce ailments in their children to draw attention to themselves.

The hearing continues.