Civil rights activists have complained about the treatment of a 28st man who was forced into hospital because he was too fat.

The Citizens' Commission on Human Rights (CCHR) has written to the East Sussex County Healthcare NHS Trust and the General Medical Council outlining concerns about the treatment of Chris Leppard.

The 23-year-old suffers from the rare Prader Willi syndrome (PWS), which leaves him craving food.

He weighed 33st when the authorities sectioned him under the Mental Health Act at Eastbourne Clinic, in Grange Road, Eastbourne, last February.

Doctors discharged him seven days later after finding no signs of mental disorder.

Mr Leppard and his mother, Anne, believe the authorities' actions were inappropriate because he suffers from a physical condition not a mental one.

The first time they knew he was to be sectioned was when four people arrived at their home in Chiltern Drive, Hastings, to take him away.

CCHR national spokesman Brian Daniels said the trust is obliged to investigate and hopes the General Medical Council will launch a separate inquiry into the case.

The group fights psychiatric abuse and is concerned by the increasing tendency to treat physical conditions as psychological ones.

Mr Daniels said: "Chris shouldn't have been subjected to that kind of treatment. What happened was absolutely appalling."

Mrs Leppard, 41, said she visited her son every day to ensure he ate properly but staff told her they could not accommodate his diet because he was not there for his weight. She claims he was fed fry-ups on a daily basis.

She said: "The authorities aren't answering why he was sectioned. He had a problem with his weight but there was nothing wrong with his mind. I want them to admit what they did to my son was wrong."

Since his sectioning, her son has become more dependent on her.

He aims to slim down to 18st and has already lost 5st in three months by following a diet administered by his mother.

An East Sussex County Healthcare NHS Trust spokesman said: "All we've done has been with the intention of helping Christopher and his family."

An East Sussex County Council social services spokeswoman said it stood by the decision to refer Mr Leppard for an assessment under the Mental Health Act and had always acted in his best interests.