The Food Safety Authority of Ireland (FSAI) has found horse DNA in burgers being shipped from Ireland to UK and Irish supermarkets.
The FSAI said the meat came from two processing plants in Ireland, Liffey Meats and Silvercrest Foods, and the Dalepak Hambleton plant in Yorkshire.
The burgers were on sale in Tesco, Dunnes Stores, Lidl, Aldi and Iceland.
A total of 27 products were analysed, with 10 of them containing horse DNA and 23 containing pig DNA.
In nine of the ten beef burger samples from these retailers, horse DNA was found at very low levels. However, in one sample from Tesco, the level of horse DNA indicated that horsemeat accounted for approximately 29% relative to the beef content, the FSAI said.
The FSAI has stated that while the products posed no danger to the public, consumers in Ireland and the UK do not have a culture of eating horsemeat and therefore would not expect to find it in their burgers.
The retailers concerned are now removing the products concerned from the shelves.