Three hospital patients have died after eating pre-packaged sandwiches contaminated with listeria, Public Health England have said.
Two of the patients died at Manchester Royal Infirmary. The third death happened at Aintree University Hospital NHS Foundation Trust.
In total, six hospital patients who were seriously ill at the two hospitals contracted listeria from the sandwiches.
Manchester University NHS Foundation Trust said it "offered our deepest condolences to the bereaved families". It added the sandwiches came from the patient menu and the ones that may have been affected have been withdrawn.
The Good Food Chain, which is based in Staffordshire and produced the sandwiches, has voluntarily ceased production while an investigation is underway.
Meat for their products had been produced by North Country Cooked Meats, based in Salford, Greater Manchester, who have also ceased production. A spokesman for the company said it "is currently co-operating fully with the environmental health and the Food Standards Agency in their investigations, and a further statement will be issued in due course."
For years some in the catering industry have warned that giving pre-packed sandwiches to patients with low immunity can carry risk.
Jim Winship, who works for the British Sandwich and Foot to Go Association, told ITV News: "Listeria is probably the main danger in terms of chilled foods going to patients with lower immune systems because they are vulnerable for that.
"It's really very concerning really that some of the hospitals carry on serving them."
A spokesman for Manchester Royal Infirmary said: “We have offered our deepest condolences to the bereaved families and sincerely regret that two of our seriously ill patients who were receiving care in Manchester Royal Infirmary contracted listeria infections linked to this outbreak.
"We are continuing to work with Public Health England, NHS England and the Food Standards Agency to support their investigation into the cases of listeria that have been identified, which may be linked to one of the Trust’s food suppliers.
"Although the risk of infection was extremely small, as soon as the Trust was informed of the findings of PHE’s investigation, a decision was made to remove the sandwiches that may have been affected from the patient menu as a precautionary measure, and an alternative supplier was established."
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."
Dr Colin Sullivan, Chief Operating Officer at the FSA 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."
PHE says listeria infection in healthy people is usually either unnoticed or may cause very mild illness but it can have more serious consequences for some people, particularly those with pre-existing health conditions and pregnant women.
Who are The Good Food Chain?
On the company's website, it boasts how "for over 20 years we have supplied prestigious Universities, Business & Industry and Sporting Venues in the UK".
The Good Food Company adds "proud to be revolutionsing sandwiches for healthcare patients" and that its products are "designed around today's patients".
It also says that its "products are handmade, using fresh ingredients and has been accredited by industry standard rewards".
The Good Food Chain also has a glowing endorsement from the Department for Health on its website which says: "Hospital food is an essential part of patient care. Good food can encourage patients to eat well, aiding their recovery from surgery or illness.
"Patients should receive food that is safe, of good quality, nutritious, well presented and served at a time convenient to them."
The Good Food Company has a production facility in Stone, Staffordshire.
Who are North Country Quality Foods?
North Country Cooked Foods produces the meat, which is distributed to North Country Quality Foods, who specialise in cooked meats, canned goods and cheese.
According to North Country Quality Foods's website, the company was established in 1967.
It is unclear what types of products The Good Food Chain buys from North Country Cooked Foods.
The company is based in Salford, Greater Manchester.