Ministers should set targets to reduce child obesity which threatens the health of the nation, according to an official report published this week.

Schools have a vital role in tackling obesity, poor diet and lack of exercise among children, says the report by Derek Wanless, a former banker asked by the Cabinet to report on how health in England could be improved.

Securing good health for the whole population calls for action to improve school meals, upgrade health and nutrition education and increase the level of physical activity among young people.

Mr Wanless’s report will be carefully read by ministers. His previous review led to a 1p increase in national insurance to secure more funds for the National Health Service.

The new report was issued as a leading NHS expert called on schools to consider banning chocolate and other unhealthy snacks.

Mr Wanless described the scale of the obesity problem as “unprecedented”.

Targets for both children and adults are necessary to ensure that good intentions are backed up by action, he said.

The number of overweight and obese children increased by more than a quarter between 1995 and 2002.

One in 10 six-year-olds is now obese and one in six 15-year-olds. Experts warn that even conservative projections show that by 2020, one in five boys and a third of girls will be obese.

The report does not prescribe in detail what action schools should take, but it praises schemes such as Yorkshire Water’s Cool Schools initiative which has put free water coolers in schools and succeeded in reducing the amount of fizzy drinks consumed by pupils.

“Schools are very important. We have not said what should be in the curriculum but schools can make a real difference by the food children are given there, the lessons they have and the amount of physical activity they do,” Mr Wanless said.

Professor Mike Kelly, director of evidence and guidance at the NHS health development agency, this week warned that obesity is now as big a problem as smoking was 40 years ago.

Speaking at a London conference, Tackling Obesity in Young People, Professor Kelly called for a debate over whether schools should ban the sale of all snacks on their premises except water, fruit, juice and milk.

Professor Kelly emphasised that schools cannot tackle the problem alone and need more support from ministers and families.

A ban on food advertising to children should also be considered, he said, a move backed by the Consumers’ Association.

Last month the Government ruled out a ban on TV food advertising aimed at children, saying it preferred to work with the industry instead.