Ministers are failing in their duty to protect primary school children from school meals high in fat, salt and sugar, say nutrition campaigners.

Amid rising fears over levels of childhood obesity in the UK, research warned of the dangers of eating typical school dinners, such as cheese fritters, roast potatoes and flapjacks.

And Education Secretary Charles Clarke was urged to act now to improve the quality of primary school meals.

The research, commissioned by the Soil Association, analysed five meals typically served in primary schools over a week.

It found that children eating meals such as cheese fritters, roast potatoes, peas and flapjacks for five days would consume 40 per cent more sodium (salt), 28 per cent more saturated fat and 20 per cent more sugar than is recommended.

They would also only receive 80 per cent of the amount of iron and 70 per cent of the amount of zinc needed for a healthy diet.

Mr Clarke recently announced he would review the standard of meals served in secondary schools.

But the Soil Association - which promotes organic and local foods - said it wanted him to act on primary schools too.

Peter Melchett, the association's policy director, said: "It is well known that most school dinners in primary schools do not provide the correct level of nutrients and give children too much fat, sugar and salt.

"But still Charles Clarke refuses to act to protect children at their most crucial stage of development.

"If children are encouraged to eat healthily in primary school, they are likely to demand good quality food as they get older."

A spokeswoman for the Department for Education and Skills said work was already under way to improve the quality of school meals.