The unusual strain of the bug, enteritidis PT 14b, has been blamed for making more than 150 people in London and Cheshire ill since early September.

The Food Standards Agency (FSA) believe the source for the outbreaks could have been Chatwins Bakery in Nantwich, Cheshire, and Patisserie Madeira, in Lambeth, south London.

But the agency has said it is still continuing its investigations.

Cross contamination

The bug causes diarrhoea, vomiting and fever.

A spokesman for the FSA said both businesses were co-operating fully with the agency's investigations.

Food businesses need to remember that they should use pasteurised egg in their raw or lightly cooked products

Dr Roger Skinner

The FSA said the Cheshire bakery was using ordinary eggs in products that were not cooked but had now stopped this practice.

Salmonella in samples from the London patisserie had indicated a risk of cross contamination which the FSA say was caused by not following "good practice".

Both businesses supplied products to a number of outlets in their region.

Dr Roger Skinner, head of the FSA's microbiological safety division, said: "Over 150 people have been taken ill and one person has died.

'At risk'

"It is possible there is a link between these cases and the use or handling of eggs.

"Food businesses need to remember that they should use pasteurised egg in their raw or lightly cooked products.

"They could be putting people at risk if they do not follow that advice.

"It is important to remember that the salmonella bug can be easily killed if eggs are properly cooked before use."

In 1989, the link between eggs and salmonella poisoning was proved and two million chickens were slaughtered.