Almost a third of schoolchildren play little or no sport, adding to fears about unhealthy lifestyles causing obesity, a new report reveals.

One in five pupils aged five to 16 play games for only an hour or less per week, and a further 12 per cent never play, according to the latest research from youth marketing experts Childwise.

It also found that girls' early enthusiasm for playing football disappears at secondary school, and that many children are not interested in the sports offered to them by their school. They would rather go horse riding, swimming or do gymnastics than play traditional team sports.

The results appear to contradict assurances from ministers that growing numbers of children are getting at least two hours of physical education a week, and threaten government efforts to stop the growth of obesity among under-11s by 2010.