A sandwich firm at the centre of a listeria outbreak at hospitals that has been linked to the deaths of five people has been allowed to restart production.
The Food Standards Agency has been investigating the Good Food Chain, based in Staffordshire, but said it does not believe the firm is the source of the outbreak.
Nine cases, including the five deaths, have been identified at seven hospital trusts around the UK where the patient is suspected to have contracted the illness from eating pre-packaged Good Food Chain sandwiches and salads.
The FSA said it is moving its focus to where the ingredients came from but has not yet determined the exact source.
The Good Food Chain has been told it can resume production after its pre-packaged sandwiches and salads were linked to the deaths of five people who ate its products in hospitals around the UK (file picture)
Supplier North Country Cooked Meats, based in Salford, Greater Manchester, has tested positive for the particular strain of the outbreak and has since stopped production.
Public Health England confirmed the number of cases linked to the outbreak remained at nine from seven separate hospital trusts.
Last week mother-of-five Enid Heap, 84, was named as one of the victims of the outbreak.
The retired chemist from Beswick, Manchester, was admitted to Manchester Royal Infirmary in March with breathing difficulties, but died on May 6 with her family at her bedside.
Also named was Beverley Sowah, 57, a retired nurse born in Jamaica who lived in Manchester. She was admitted to the same hospital to receive treatment for advanced breast cancer on April 15 but died 11 days later.
Lsst week the NHS identified University Hospitals of Derby and Burton as one of the hospital trusts affected by a patient death.
There was another death at Aintree University Hospital NHS Foundation Trust in Liverpool, and one at University Hospitals of Leicester NHS Trust.
Three other trusts had diagnosed listeria cases linked to the outbreak with no deaths – two cases at Western Sussex Hospitals NHS Foundation Trust, one case at Frimley Health NHS Foundation Trust and one at East Kent Hospitals University NHS Foundation Trust.
Meanwhile Good Food Chain confirmed its Staffordshire headquarters has undergone a deep clean and added it had not resumed production yet even though it had been given the green light.
A spokesman for the company said: ‘The FSA has confirmed that we are not the source of the listeria strain in question, and that we follow ‘best practice for manufacturing, cleaning, and environmental standards’.
‘While this means we can now resume production, we have not yet taken any decision about whether it is viable to do so.
‘Production therefore remains suspended for the time being.’
The FSA added an enhanced set of food safety measures have been put in place at the company’s base and that Staffordshire County Council would be carrying out strict monitoring over the next three months.
The Good Food Chain will also have to reapply for FSA accreditation before it can supply the NHS with food again.
Dr Colin Sullivan, Chief Operating Officer at the FSA said: ‘This is a complex investigation, but we have worked to swiftly identify and remove from the food chain the products linked to these hospital cases.
‘Our investigations are now focused on where the outbreak strain originated from and subject to strict verification and ongoing monitoring by Stafford Borough Council, The Good Food Chain company is now able to restart production.
‘The company will be carefully monitored to ensure public health continues to be protected. Our thoughts remain with the families of those who have passed away.’
Councillor Jonathan Price, the Cabinet Member for Environment at Stafford Borough Council, said: ‘We have worked tirelessly with the Good Food Chain and are reassured that their manufacturing processes, cleaning procedures and environmental standards meet those we expect for producing ready to eat foods.’
‘But our work does not stop there as the health of the public is our top priority.
‘So we will continue collecting environmental swabs from surfaces at the business, taking samples of food, and working with The Good Food Chain to ensure they have control measures in place to thoroughly assess those supplying products to them.’
All confirmed cases to date have been linked to sandwiches produced by The Good Food Chain.
The company voluntarily ceased production on 5 June and withdrew all products which remained in date.
Evidence suggests that all individuals ate the affected products in hospitals before the withdrawal took place on the 25 May.

The firm confirmed its base in Staffordshire, pictured, has undergone a deep clean but that it has not started production again because it was investigating ‘whether it was viable’
Public Health England added no cases of listeriosis linked to this outbreak have been confirmed in people outside of hospital settings and therefore the risk to the public remains low.
North Country Quality Foods voluntarily stopped distributing supplies on 3 June and a withdrawal of all ready to eat products has been carried out on a precautionary basis.
The products supplied by North Country Quality Foods to other businesses have not led to any reported cases to date.
Public Health England confirmed it had found 20 other cases of listeria in the two months since the first case linked to the Good Food Chain was discovered.
But the body confirmed none of these 20 were linked to the outbreak or each other and were in line with the normal amount of cases they would expect to see, with around 166 cases identified on average in the UK each year.