One in three children aged two to 15 is now classed as overweight or obese, according to figures released yesterday, prompting warnings of a "public health time bomb".

Despite the fact that the statistics also showed that people are eating better and exercising more, there were renewed calls for government action to promote healthier lifestyles and curb junk-food advertising aimed at children.

The figures, culled from the annual Health Survey for England and released by the Health and Social Care Information Centre, also show that the number of obese children aged 11 to 15 has almost doubled over the past ten years to reach a quarter of the population - increasing from 14 per cent to 24 per cent for boys and from 15 per cent to 26 per cent for girls. Among children aged two to 10, the figure went up from 10 per cent for boys in 1995 to 16 per cent in 2004, and from 10 per cent for girls in 1995 to 11 per cent in 2004.

For all children aged between two and 15, the figure for those either overweight or obese has risen from 24 per cent in 1995 to 33 per cent in 2004. The figures are the same for both sexes.

The survey also showed that one in four adults is now considered obese. The number of obese men has almost doubled since 1993 - from 13 per cent to 24 per cent in 2004. For women, the figure has gone from 16 per cent in 1993 to 24 per cent in 2004.

But the survey also shows that number of men eating at least five portions of fruit and vegetables a day increased from 22 per cent in 2001 to 24 per cent in 2004, while the figure for women went from 25 per cent to 27 per cent. The number of men exercising for 30 minutes, five or more times a week, increased from 32 per cent to 35 per cent between 1997 and 2004, and from 21 per of women to 24 per cent during the same period.

Professor Colin Waine, chairman of the National Obesity Forum, said the figures revealed a "public health time bomb" because research showed that 11 to 15-year-old children who are obese are twice as likely to die by the age of 50. He said: "It augurs badly for the future health of the population. We are in danger of raising a generation of people who have a shorter life expectancy than their parents."

Amanda Eden, care adviser at Diabetes UK, said: "A firmer line needs to be taken to force the food industry to adhere to labelling guidelines so people know what's in the food they buy. They also need to ban junk-food advertising to kids and find more ways of encouraging people to exercise."

Caroline Flint, the Public Health minister, said the Government would continue working "to meet our target to halt the increase of childhood obesity by 2010".