Children should be forced to do more school sports to tackle the "ticking timebomb" of obesity, a Sussex MP has warned.

Tim Loughton, Tory MP for East Worthing and Shoreham, said "horrific"

forecasts that suggested half of all children would be dangerously overweight by 2050 demonstrated how important it was to tackle the problem urgently.

He lamented the growth of a "no ball games here" culture in towns and cities and said: "We now live in a culture where the Playstation has taken over from the playground and children are getting obese younger.

"We desperately need to increase the amount of time that children get involved in physical activity and to encourage healthy eating. Kids need to be getting out and running around more."

Mr Loughton described obesity as "the ticking time bomb facing the health service today".

This week the Government revealed 86 per cent of pupils participated in at least two hours of physical education and school sport per week in 2006-07, up from 62 per cent in 2003-04.

Speaking at Prime Minister's Questions, Gordon Brown said schools would be expected to work towards a target of five hours of activity a week so "every young child will have the chance to enjoy a range of sports in their schools".

But Mr Loughton said the Government's initial target had been "woefully inadequate" and he called on ministers to seek inspiration from Scandinavia, where children have up to 11 hours of physical activity a week.

He also questioned whether schools would be able to achieve the new targets unless the Government made "fundamental changes" to provide extra time for competitive sports.

The largest British study into obesity, compiled by 250 experts and backed by the Government, has warned the crisis is so severe that it could take at least 30 years to reverse.

The report, published on Wednesday by the Government's Foresight think-tank, said excess weight was now the norm and dramatic and comprehensive action was required to prevent most people being obese by 2050.

Health Secretary Alan Johnson said the Government had already taken the "bold" measure to ban the advertising of unhealthy foods during children's TV programmes.

However, it was "determined to go further" if the evidence supported the need to do so.

The minister called for a "national debate" and said employers could help by providing workers with loans for bicycles, subsidising gym membership and providing fruit at meetings instead of biscuits.

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