The disturbing findings, published in a report by the Children's Society today, also show that 70 per cent are so unhappy about their bodies that they are on a diet some or all of the time.

The report comes just months after a Unicef study of 21 industrialised countries found Britain's children were the unhappiest in the Western world.

The study – the fifth part of the Children's Society's Good Childhood Inquiry – seems to re-inforce the view that children in Britain are increasingly unhappy with their lot. A sixth report on values is planned before the final report next year.

Today's report on health draws on evidence from children, young people, adults and professionals gathered since 2005.

In one survey of 8,000 young sters aged 14 to 16, 27 per cent agreed "I often feel depressed" and in an online vote, by CBBC Newsround, 22 per cent said they felt bad or really bad because of pressure from school, their peers, bullying, family expectations and their looks.

Prof Stephen Scott, from the Institute of Psychiatry, said: "Many respondents to the inquiry shared the belief that wellbeing depends on good relationships – especially within the family – and on a sense of purpose and on freedom. To achieve this, child mental health and wellbeing must be everybody's business."

Children's Minister Kevin Brennan insisted most young people in Britain were healthy and felt good about themselves, but admitted there were problems.

"That is why we issued our Children's Plan, which aims to make this the best place in the world to be a child," he said.


Unhappy Children

27 per cent often feel depressed.

70 per cent are on a diet some or all of the time.

22 pent feel bad or really bad about their health.

One in 10 didn't do any exercise in the last week.

13 per cent of girls and 10 per cent of boys aged 10 to 15 suffer mental health problems.