Celebrity chef Jamie Oliver and health experts have been asked to help the British government in tackling the problem of obesity in primary school children.

David Cameron said it was “disturbing” that 10 per cent of children are obese when they begin primary school but the figure rises to 20 per cent by the time they leave.

The Prime Minister said obesity was an “enormous health challenge” for the country with a “vast” cost to the NHS.

Mr Cameron said: “I think the point I’d make when you look at the most disturbing figures it’s the fact that 10 per cent of children go into primary school obese, but 20 per cent are coming out of primary school obese and so it’s this primary school period where we really can do better.”

He said he had “tasked the Department of Health, Department for Education, working with Jamie Oliver and others, to look at this period and think ‘well, what can we do better?’”

The government is set to produce a childhood obesity strategy in the autumn and experts including Oliver were recently invited to Downing Street for a one-off session so the Prime Minister could hear their views about the challenge.