Children with mental health problems are being put at severe risk by long waiting lists to see a psychiatrist and the closures of specialist units designed to treat them, doctors have warned.

NHS trusts are cutting in-patient beds for young psychiatric patients at a time when the number of children suffering from mental illness is increasing.

Youngsters are waiting an average of more than six months to see a child psychiatrist and are denied the most appropriate treatments for their problems.

There is now growing criticism that children with mental health problems are being treated with a "chemical cosh" of prescription drugs because of budget constraints on other therapies, such as counselling.

Adrian Worrall, of the Royal College of Psychiatrists, said: "All the evidence shows the most effective way to help young people is to catch them early, before their problems translate into other problems such as drink and drugs and crime.

"All too often, children are not being picked up, are not receiving fast access to treatment or appropriate treatment when they do get it. This will have long-term consequences for everyone."

One in 10 children has a significant mental health problem such as depression, a propensity to self-harm, anorexia or other disorders. A survey of 1,300 GPs by the medical magazine Pulse found that the average wait for an appointment with a child psychiatrist was 188 days.

Children had to wait 79 days before even an initial assessment was made by the Child and Adolescent Mental Health Service (CAMHS), and a further 102 days before treatment; 93 per cent of family doctors admitted they had to prescribe antidepressants because of a lack of alternative therapies, despite safety concerns surrounding the use of some of the drugs for young people.

Phil Johnson, the editor of Pulse, said: "The figures we have uncovered are simply appalling. It is a scandal that some of the most vulnerable patients in the country are left languishing on waiting lists because apparently mental health is not seen as a priority."

Three of the country's 13 specialist children's psychiatric in-patient units have closed since 2003. A fourth, the Park Hospital unit in Oxford, is also threatened with closure, despite being considered one of the best in the country. Doctors at the unit were told a few months ago that it was being moved to new buildings. They have now been told that the in-patient service is to be shut. Experts believe pressure on the local NHS trust to reverse a huge financial deficit is behind the U-turn and they say two similar units are also threatened with closure.