An independent group which monitors the quality of food is challenging the claims of manufacturers to have reduced the levels of salt in their products.

According to the Food Commission, the salt content of crisps has nearly doubled over the past 25 years, and some products aimed at children contain more salt in one serving than the recommended intake for a whole day.

The commission took the levels of salt in crisps, white bread, canned baked beans and tinned tomato soup and compared them with the same products from 1978.

It is very hard for people to cut back on salt because it is hidden in everyday products Kath Dalmeny Food Commission

The survey, published in Food Magazine, found the amount in crisps had almost doubled.

Levels in baked beans had also risen, while levels in tomato soup and white bread had fallen only slightly.

The commission also looked at the salt content in some popular children's food and compared it with government recommended maximum daily salt intake for one to six-year-olds.

They found a Burger King children's meal, a small can of Heinz Telly Tubbies pasta shapes and a single portion of a Dairylea Lunchables would each take a six-year-old child well over the recommended daily limit in just one serving.

Heart attacks

Eating high levels of salt is linked to high blood pressure, which is the main cause of strokes and a major factor in heart attacks.

Food Commission researcher Kath Dalmeny said the food industry had to take greater responsibility for public health and reduce salt in processed food.

She said: "The government has acknowledged that processed foods are the main source of salt in people's diets.

"Most people, including children, eat about twice as much salt as the recommended maximum level.

"However it is very hard for people to cut back on salt because it is hidden in everyday products such as bread, canned soup and baked beans."

The commission also criticised the Football Association and nine Premiership football clubs for promoting junk foods and sugary drinks to children.

The Food and Drink Federation said the commission's claims were "out of date, out of touch and based on self-selecting surveys".

Martin Paterson, its deputy director general, said: "UK bread manufacturers have, for example, reduced salt across the product range by a quarter since the 1980's which has included reductions confirmed in a recent Food Standards Agency survey of breads.

"The federation is currently working with the FSA to identify more products where reductions in salt have been achieved, and might be further reduced."