Three hospital patients have died after eating pre-packaged sandwiches linked to a listeria outbreak.
An investigation has been launched into the source of the infection, related to products supplied by The Good Food Chain, Public Health England (PHE) said.
Cases of listeria infection were found 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 Food Standards Agency, 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."
Sandwiches and salads linked to the cases have been withdrawn and The Good Food Chain has voluntarily ceased production.
The business was supplied with meat produced by North Country Cooked Meats, which has since tested positive for the outbreak strain of listeria and also stopped production.
The affected products have been withdrawn from hospitals.
Listeria infection is rare and usually causes a mild illness in healthy people.
However it can have more serious consequences among those with pre-existing medical conditions, pregnant women and those with a weak immune system.
Dr Colin Sullivan, chief operating officer at the Food Standards Agency (FSA), which is helping with the investigation, said: "Our sympathies are with the families of those patients who have tragically passed away.
"We have taken action along with local authorities to minimise the risk based on the evidence so far.
"The FSA will continue to investigate how the outbreak occurred and if further steps are required to protect vulnerable groups."