Taking part in games like tennis, golf or bowling on consoles such as the Wii can burn four times as many calories as playing more traditional computer games, enough to keep waistlines in check, they claim.

Computer games have long been blamed for the growing obesity crisis, which has left almost one in four British adults extremely overweight.

Critics claim that the games encourage sedentary lifestyles and divert children away from playing more physically demanding games like football or rounders.

But now scientists say the new games, in which players holding joysticks mimic the actions involved in sports to control an on screen character, are a good way of keeping fit.

Players can burn up to 150 calories in 35 minutes while imitating the motions of their favourite sport stars in order to "hit" tennis balls or "swing" golf clubs, scientists found, roughly the same amount as a brisk walk.

Previous studies have suggested that expending a similar amount of energy every day could be enough to help most people avoid gaining weight.

"Preventing weight gain requires an energy adjustment of approximately 150 [calories] per day," according to the authors of the study, Robin Mellecker and Alison McManus, from the University of Hong Kong.

"The four-fold increase in energy expenditure when playing the (active game) would fill the proposed energy gap, if this game were played for 35 minutes a day."

The study, which looked at 18 children with an average age of 9 years old, also found that the new type of game could significantly raise a player's heart rate.

Details of the study are published in the journal Archives of Pediatrics & Adolescent Medicine.

Doctors classify obesity based on a person's Body Mass Index (BMI), a measurement of their weight compared to their height.

A BMI of between 20 and 25 is considered normal, while a BMI of more than 30 is obese.

Earlier this year Nintendo launched the Wii Fit, designed to keep players in shape.

The researchers now want to see whether the new games will encourage children to exercise more as they become adults.

By Kate Devlin Medical Correspondent
Last Updated: 6:01PM BST 01 Sep 200