Thousands of children with behavioural problems are being prescribed anti-psychotic drugs with dangerous side effects, doctors warn.

The powerful tranquillisers, designed to treat psychosis and schizophrenia in adults, are being used to calm children who are simply hyperactive.

Around 8,000 youngsters are taking anti- psychotics such as Risperdal and Zyprexa despite the fact that these have been linked to a host of health problems from diabetes to brain damage, BBC1's Panorama reports.

Although some are prescribed for schizophrenia and related conditions, many are given to children with attention deficit hyperactivity disorder and other behavioural problems.

Dr Tim Kendall, of the Royal College of Psychiatrists, said he knew of children as young as ten being given the schizophrenia drugs for unruly behaviour, sometimes for as long as five years.

He said that the drugs should be considered as a last resort in the treatment of hyperactivity.

And he added: "A generous understanding would be to say that doctors have reached a point where they don't know what else to offer and they haven't got the right supports to help parents in difficult circumstances.

"I think perhaps there is no real excuse for prescribing drugs which are associated with such severe side-effects."

The consultant psychiatrist, who is heading a team drawing up Government guidelines on the treatment of ADHD, said: "Everyone agrees that if there are alternatives we should be exploring these alternatives and looking at what psychological treatments can work and what helps the parents and the teachers."

The warnings come amid growing concern that ADHD is being diagnosed in children suffering from nothing more than natural boisterousness.

In March this year Dr Robert Spitzer, the U.S. psychiatrist who first identified the ADHD, admitted that up to a third of cases could have been misdiagnosed.

Tonight's Panorama also reveals disturbing evidence that other drugs, much more commonly used to treat ADHD, do not work in the long term.

A study in the U.S. suggests that while medication such as Ritalin and Concerta is effective initially, the effects wear off after three years of treatment.

The drugs, taken by around 55,000 British children at the cost to the NHS of £28million a year, stunt growth, the researchers discovered.

Many children take the controversial drugs for years at a time though they have also been linked to heart problems, dizziness and insomnia, and blamed for a string of deaths in the UK and abroad.

Researcher Professor William Pelham, of the University at Buffalo in New York state tracked the health and treatment of 600 children with ADHD for six years.

He warned: "They had a substantial decrease in their rate of growth, so they weren't growing as much as other kids in terms of their height and weight.

"In the short-run [medication] will help the child behave better, in the long-run, it won't. And that information should be made very clear to parents."

The makers of Concerta and Risperdal, Buckinghamshirebased Janssen-Cilag, said the drugs were "very valuable treatments".

Eli Lilly, the U.S.-based maker of Zyprexa, said it had never promoted the anti-psychotic for the treatment of ADHD and did not intend to do so.

The makers of Ritalin, Swissbased Novartis, were unable to comment last night. The Panorama programme will be shown on BBC1 at 8.30pm tonight.