High levels of potentially cancer-causing chemicals have been discovered in more than 20 brands of soy sauce sold in Britain.

High levels of potentially cancer-causing chemicals have been discovered in more than 20 brands of soy sauce sold in Britain.

The Food Standards Agency said that nearly one-quarter of the 100 samples it tested in a survey last year gave cause for concern. However, it said the carcinogenic chemicals could be harmful only if used with most meals over a long period of time, with British-based Chinese communities facing the greatest threat to health.

The agency said none of the products from big supermarkets posed any safety concerns and that the affected sauces were mostly sold in specialist oriental food shops and are likely to be used by the Chinese restaurant trade.

The affected products, which included a chicken marinade, oyster sauces and "superior" soy sauces, were imported from China, Hong Kong, Taiwan and Thailand. Some were believed to be counterfeit.

Three of the sauces came under the Golden Mountain label, based in Thailand. Its soya bean sauce had the highest levels in the survey and two teaspoons a day of it would be enough to exceed European safety limits, due to come into effect next year, by up to 20 times. Sauces from the Lee Kum Kee Co, based in Hong Kong, accounted for another five. However, the agency said the sauces formed a small proportion of the total UK market.

The study discovered the chemical 3-MCPD, which is common in many foods, at levels well above the EU legal limit in 22 cases. About two-thirds of those samples also contained 1,3-DCP, which experts advise should not be present at any levels in food. The agency advised shops to ask for proof from suppliers that soy sauces sold to them had been tested. A leaflet has been issued to the Chinese community and the restaurant trade.

The agency is planning a follow-up survey to its study, which will be its third examination of the soy sauce market. Previous studies of levels in other foods such as biscuits, breads, cheeses and burgers have shown 3-MCPD to be present, but at much lower levels.

Suzi Leather, the agency's deputy chairwoman, said: "All of the affected products should be removed from the shelves and consumers should throw away any that they may have.

"We are particularly concerned to protect people who have high levels of consumption, as they will be most at risk from the harmful effects of these chemicals.

"This is most likely to be people from East and South East Asian communities. Soy sauce can be produced without these chemicals and we expect swift action from the industry to ensure that the planned EU legal limits are met."