Two more hospital patients have died after eating pre-packaged sandwiches and salads linked to a listeria outbreak, Public Health England has confirmed.

They are among nine patients in England who have been affected, with the investigation having previously confirmed the deaths of two patients from Manchester Royal Infirmary and one at Aintree Hospital in Liverpool.

Sandwiches and salads supplied by the Good Food Chain have been withdrawn and production stopped. The company had been supplying 43 NHS trusts across the UK with meat produced by North Country Cooked meets, which had tested positive for listeria.

Public Health England (PHE) has yet to say where the latest patients to die had been treated.

In a statement on Friday, PHE said: "Since the multi-agency investigation began into listeria cases linked to sandwiches and salads, Public Health England has been analysing previously known cases of listeria from the past two months to see if they are linked to this outbreak.

"Whilst any risk to the public remains low, PHE's Whole Genome Sequencing analysis has identified an additional three cases of listeria linked to this outbreak.

"This brings the total number of confirmed cases to nine. All of the cases of listeria infection were in hospital patients in England.

"Sadly, one of the seriously ill six patients PHE confirmed last week has since died.

"One of the patients confirmed today as linked to the outbreak had already died. This brings the number of deaths linked to this outbreak to five."

The supplier, The Good Food Chain, meat producer North Country Cooked Meats and distributor North Country Quality Foods have voluntarily ceased production during the investigation, PHE said.

"The affected sandwiches and salads were withdrawn from hospitals when the links to the listeria infections were first identified and the multi-agency team then advised NHS organisations not to provide any Good Food Chain products to vulnerable patients.

"Evidence suggests that all individuals ate the affected products before the withdrawal took place in hospitals on the 25 May 2019. The food chain investigations continue."

Dr Nick Phin, deputy director at the national infection service at PHE, 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."

In a statement, the Good Food Chain said: "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 (Food Standards Agency) and other authorities, and will continue to do so".

North Country Cooked Meats said previously: "At this stage the company is currently co-operating fully with the environmental health and the FSA in their investigations, and a further statement will be issued in due course."