The Food Standards Agency (FSA) said a quantity of frozen meat being stored in Northern Ireland had been found to contain 80% horsemeat.
The FSA said the meat tested at Freeza Meats, in Newry, on the border with the Republic, was potentially linked to the Silvercrest factory, the site where the original contamination was discovered.
The meat has not entered the food chain. The FSA said:
Of the 12 samples from the suspect consignment that have been tested, two of the samples came back positive for horse meat, at around 80%.
The investigation into the traceability of these raw materials and their source is under way. As this meat was detained, it has not entered the food chain.
More top news
Nina Nannar has an unforgettable encounter with the man who has run the Chanel couture house for more than 30 years.
This afternoon will remain fine and settled for central and western areas of Britain.
A paramedic left her own wedding to help her family following a car crash.