Health chiefs are investigating two deaths linked to a surge in food poisoning cases.
The number of cases has trebled in the last year as investigators examine links to eggs sourced from Spain, the Food Standards Agency (FSA) said.
A total of 14 clusters in England and Wales have been linked to a number of different catering establishments and one care home, the FSA said.
To date, 443 cases have been reported to the Health Protection Agency this year, compared with 137 in 2008.
It is understood two deaths of people at the care home in Sunderland have been linked to salmonella poisoning.
An FSA spokesman said: "Although there is no conclusive evidence yet, the clusters may be linked to eggs sourced from outside the UK and used in these establishments.
"Investigations are ongoing into a possible link to eggs sourced from an approved establishment in Spain, and the UK and Spanish authorities are working in close cooperation to investigate this."
The rise in cases has been noticed since mid-August, the FSA said.
Salmonella is one of the most common causes of food poisoning in the UK and is sometimes found in unpasteurised milk, raw meat and poultry, as well as eggs and products containing raw egg.
The FSA said there was "a very low incidence" of salmonella in UK eggs.
