The first national campaign to get children fit was unveiled by the Health Education Authority (HEA) on Wednesday.

Called Young and Active?, it says children can improve both their mental and physical health through regular exercise.

It recommends that children who are not used to exercise should start with half an hour a day and build up to an hour.

The campaign suggest specific roles for organisations such as schools, youth groups, local government, health organisations and the media in getting Britain's youth into shape.

Health Minister Tessa Jowell said partnership working was the only way the campaign would work.

Obesity

Nick Cavill of the HEA said: "Many young people are not active enough to benefit their health.

"The numbers of overweight and obese children are increasing and many young people have symptoms of depression and anxiety."

The HEA says regular exercise can make children feel happier and more confident.

It can also lower blood pressure and reduce the chance of children developing diseases in later life.

Schools minister Charles Clarke said new measures to save school playing fields from closure and the establishment of after school clubs and 26 sports colleges for young people would give children the space they needed for exercise.

Lectures

A recent report for children's charity Barnardo's found that children wanted to get fit, but did little to achieve this.

They said they did not want to be lectured by adults about health.

Seven out of 10 of those questioned considered themselves "fairly fit".