SHOPS and food companies have less than 24 hours to identify all products containing the banned food dye Sudan I, the Food Standards Agency said.

More than 400 products have been recalled so far after they were found to contain the dye, which has been linked to an increased risk of cancer.

The FSA said firms which did not meet the deadline could face prosecution.

Local authorities are also checking that potentially affected foods supplied to schools and hospitals by two catering companies are being withdrawn.

The caterers, 3663 and Brakes, which also hold major contracts with pubs and restaurants, have recalled all potentially- contaminated items.

The alert was sparked when a consignment of Crosse and Blackwell Worcester Sauce, made by Premier Foods, was found to contain chilli powder contaminated with the banned Sudan 1 dye.

Sudan 1 is normally used as a colouring in solvents, oils, waxes, petrol, and shoe and floor polish.

Experts warn it could contribute to an increased risk of cancer, although they add there is unlikely to be an immediate risk to health.

A spokesman for the Food Standard Agency (FSA) said yesterday local authorities were checking that potentially-affected products were being withdrawn.

"Some affected Worcester sauce produced by Premier Foods may have been used in the catering sector," he said.

"Premier Foods are responsible for ensuring these products are withdrawn.

"The risk is very small. Local authorities are routinely asked to inform and check that food businesses - including the catering departments of schools and hospitals - are withdrawing affected products. This is a standard request."

Premier Foods insisted it was doing all it could to resolve the problem.

A spokeswoman said: "Premier Foods are taking the matter incredibly seriously and they are investigating all factors but they are not making any further comment at the moment."

The Department of Health said it was not possible to pinpoint hospital food to a particular catering company.

"There is no one supplier of hospital food," a spokesman said.

"Individual hospital trusts make their own arrangements with suppliers and the FSA advice is for hospital trusts to contact their local suppliers for more information."