Celebrities should use their considerable influence to advocate a healthy diet to children rather than promote junk food products, according to proposals to be discussed by the Food Standards Agency board.

The FSA chairman, Sir John Krebs, described the growing problem of obesity among children as a "ticking time bomb" as he unveiled the recommendations, which also include changing the role of television advertising to children.

"We are all responsible for taking practical action that will improve our children's diet and health. While parents and children have personal responsibility and make their own choices, our aim is to help them help themselves," said Sir John.

"The ticking time bomb that is childhood obesity is something that none of us can afford to ignore: schools, the government, regulators or the food and advertising industries."

The proposals come as McDonald's tries to appease its critics by reducing the salt content of its chips and introducing salads in their fast food outlets.

The FSA proposals, which also include issuing manufacturers with advice on "acceptable" levels of salt, sugar and fat, are the result of a lengthy consultation on childhood obesity, which meets on Thursday to discuss the ways in which food is promoted to children.

Other measures proposed include clearer nutritional labelling and more healthy choices in school vending machines.

The average child in the UK watches the equivalent of 217 adverts a week, according to figures from the FSA. Of these 41% are for food products, with 70% for sweets, fast food, breakfast cereals with added sugar, savoury snacks and soft drinks.

The FSA says "redressing the balance in advertising during children's TV slots would be likely to have some beneficial effect".

It is also recommending a new "signpost" logo on packaging to help shoppers decide how healthy a product is.

However, Martin Paterson, the deputy director general of the Food and Drink Federation, expressed doubts about the proposals.

"Both government and industry must be careful not to patronise consumers, telling individuals what's right or wrong for them to eat," he said.

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