Thousands of children with autism in the UK could benefit from taking drugs such as Prozac, a US psychiatrist said yesterday.

Professor Eric Hollander, from the Mount Sinai medical centre in New York, said a third of children diagnosed in the United States were on antidepressants and British children were being under-treated. Although the drugs are not licensed for autism, he said there was evidence they could reduce its symptoms, enabling some children to travel on public transport or go to mainstream schools.

It is argued that those drugs may help autistic children, who are obsessed with routine and get distressed if the unexpected happens.

Doctors in Britain have been warned not to prescribe antidepressants for children and adolescents following evidence that the pills may make them become suicidal. Research Autism, a branch of the National Autistic Society, warned that such drugs had worrying side-effects in autistic children. "We advise caution," a spokesman said. "There has not been enough research to be able to give a clean bill of health to this treatment."

Professor David Healy, whose research led to the warnings, said: "These drugs have been around for the last 20 years and if there really was any substantial benefit it would have been found a long, long time ago."