An investigation is under way after Cadbury withdrew a million chocolate bars which may have been contaminated with a rare strain of salmonella.
The company says the recall - while the Food Standards Agency and the Health Protection Agency investigate - is precautionary and that the risk is low.
But a bacteriologist says there is no safe level for salmonella in chocolate.
The possible contamination has been traced to a leaking pipe at a Cadbury's plant in Herefordshire in January.
Samples were sent to an independent laboratory after the leak was discovered at the Marlbrook plant, and the montevideo strain of salmonella was identified.
'Precautionary measure'
Cadbury's European president Matthew Shattock told BBC Radio 4's Today programme the recall decision was made after the FSA revealed there had been an increase in the number of salmonella cases this year.
"We decided to conduct a precautionary recall to reassure our consumers and the public at large to minimise any confusion as to the quality of our products," he said.
Salmonella is a common cause of food poisoning but the montevideo strain is very rare.
There have been 45 cases in the UK in the last four months, compared with just 12 in the same period last year.
But a Health Protection Agency spokeswoman stressed that at the moment there was no evidence for a link between the increase in cases and the Cadbury recall.
Mr Shattock said the firm was "absolutely satisfied" its products were safe to eat.
"We identified a problem early. We corrected it and fixed it," he said.
Cadbury said the levels of contamination were "significantly below the standard that would be any health problem".
It said people who had eaten one of the affected bars should not be worried about the risks but could contact the company for a refund.
However, bacteriologist Professor Hugh Pennington of Aberdeen University told BBC News that the only safe level of salmonella in chocolate was "zero".
"The fat in chocolate actually preserves the salmonella from the normal intestinal defences, so you don't have to eat very many salmonellas to get infected.
"It's about a thousand times less than if you're eating it from traditional sources like meats," he said.
The factory at Marlbrook generates 97,000 tonnes of milk chocolate crumb every year.
It processes 180 million litres of fresh milk, 56,000 tonnes of sugar and 13,000 tonnes of cocoa liquor annually in the production process.
The crumb is transported to other sites at Bournville, near Birmingham, and Somerdale, near Bristol, to be blended with cocoa butter and turned into milk chocolate.
A Cadbury spokesman said the company had been manufacturing chocolate for more than 100 years and always treated public wellbeing as its "highest priority".
The free helpline number for Cadbury is 0800 818181.
Uneaten products should be returned to Cadbury Recall, Freepost MID20061, Birmingham B3O 2QZ, and a refund will be given.
http://news.bbc.co.uk/1/hi/5112470.stm