Three hospital patients have died following an outbreak of listeria.
An investigation has been launched into the source of the infection, which is linked to pre-packed sandwiches supplied by The Good Food Chain, Public Health England said.
The cases of listeria infection were in six seriously ill hospital patients.
Those who died were at Manchester University NHS Foundation Trust and Aintree University Hospital NHS Foundation Trust in Liverpool.
Dr Nick Phin, deputy director at the national infection service, at PHE, said: "Our thoughts are with the families of those patients who have died.
"We, along with the FSA, colleagues in local authorities and the NHS have worked quickly to determine the likely cause of this outbreak and taken action to reduce the risk to the public's health.
"To date, there have been no associated cases identified outside healthcare organisations, and any risk to the public is low."