A criminal investigation is under way into allegations that a rogue meat supplier falsely labelled huge quantities of foreign pork as British.
The Food Standards Agency (FSA) is also looking into claims that the firm also mixed rotten pork with fresh meat.
It is understood the meat may have ended up in many UK supermarkets.
Farmers Weekly, which first reported the story, said that the company was passing off industrial-scale quantities of foreign pork as British.
It said this may have been in products up until at least 2020 and could have been included in many items such as ready meals, quiches and sandwiches sold in a number of UK supermarkets, with schools, hospitals, care homes and prisons also indirectly supplied.
The FSA is not naming the business involved while it continues to gather evidence and so as not to prejudice any possible future action by the courts.
No indication
Based on the investigation so far, the agency said there was no indication that food was unsafe or there was an increased risk to consumers.
Emily Miles, chief executive of the FSA, told the BBC: "Criminal investigations take time and need to be done with due process and fairness. The FSA will work tirelessly on behalf of consumers to ensure that this criminal investigation is done to the highest-possible standards."
Retail industry lobby group, the British Retail Consortium said it could not comment on an ongoing investigation.
"Whilst we cannot comment on an ongoing investigation, retailers will support the FSA with its investigation into the individual supplier in question," it added.
It is understood that the FSA's National Food Crime Unit started its initial investigation into the firm in September 2021.
Earlier this month, it emerged that the unit was also investigating potential food fraud involving pre-packed sliced beef which was labelled as British but came from South America and Europe.
A supermarket south of the border was forced to remove products from its shelves.