Five people are now known to have died following a national listeria outbreak connected to pre-packed food.
Public Health England (PHE) confirmed today it was now investigating nine cases - five of which have proved to be fatal.
The nine cases are linked to seven different hospital trusts across England.
Two of those patients were being treated at Manchester Royal Infirmary, run by Manchester University NHS Foundation Trust, and a third at a hospital run by Aintree University Hospital NHS Foundation Trust in Liverpool.
A PHE spokesman said the NHS are not naming the trusts associated with the two new fatalities as family members are still being informed.
However, the Manchester and Aintree trusts confirmed that neither of the new deaths are linked to them.
It is understood four other patients remain seriously ill at hospitals across the country.
Public Health England said the cases are linked to sandwiches and salads supplied by The Good Food Chain, a company based in Stone, Staffordshire.
The Good Food Chain has voluntarily ceased production while the investigation continues.
The business was supplied with meat by North Country Cooked Meats, a Salford company, that has since produced 'a positive test result for the outbreak strain of listeria', PHE added.
North Country Cooked Meats, and North Country Quality Foods, the distribution arm of the business, has also voluntarily ceased production.
According to PHE, evidence suggests that the affected sandwiches and salads were eaten prior to May 25.
Dr Nick Phin, of Public Health England, said: "To date, there have been no patients linked to this incident outside healthcare organisations, but we continue to investigate.
"Swift action was taken to protect patients and any risk to the public is low.
"PHE is continuing to analyse all recent and ongoing samples of listeria from hospital patients to understand whether their illness is linked to this outbreak."
Dr Colin Sullivan, chief operating officer at the FSA added: "Our sympathies remain with the families of the 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 the cause of the outbreak to prevent a reoccurrence."
Sandwich supplier The Good Food Chain said in a statement: "Our thoughts and deepest sympathies are with the families of those who have died and anyone else who has been affected by this outbreak.
"The underlying cause of it remains unclear.
"We understand that the investigations being carried out are complicated and will involve a number of stakeholders, but we hope the authorities will pursue their inquiries with all urgency so the wider industry can learn any lessons as soon as possible, and so those affected do not have to wait too long for answers.
"For our part, we are co-operating fully and transparently with the FSA and other authorities, and will continue to do so."
Last week, a spokesperson for North Country Cooked Meats told the M.E.N: "At this stage the company Is currently cooperating fully with the environmental health and the FSA in their investigations and a further statement will be issued in due course.”
