The UK's Food Standards Agency has issued a warning to people with allergies to milk, wheat and mustard that certain packets of Walkers crisps have been mislabelled.

The FSA said Walkers Snack Foods, a division of US snacks and soft drinks giant PepsiCo, had inadvertently packed some cheese and onion flavoured French Fries into bags labelled as ready salted flavour.

The mislabelled bags of French Fries are sold individually. Some people with allergies to milk, wheat and mustard may have a severe reaction to the cheese and onion flavouring, including possible anaphylactic reactions.

It is possible that up to 11,000 wrongly labelled packets are in circulation. Although the company has not been able to verify where the packets have been distributed, it is most likely that this product will be found in small retail outlets, pubs and vending machines.

The affected products have a 'Best before' date of 26/02/05 and a product code between GBC303 318d and GBC303 319d inclusive.