Four major supermarket chains operating in Britain are withdrawing a number of beef products after horse DNA was found in frozen burgers sold in the UK and Ireland by Aldi, Iceland, Lidl and Tesco.
The Food Safety Authority of Ireland (FSAI), which made the discovery, said the burgers were produced by two processing plants in Ireland, Liffey Meats and Silvercrest Foods, and Dalepak Hambleton in the UK.
In nine of the 10 burger samples from the four retailers, and from the Irish chain Dunnes Stores, horse DNA was found at very low levels. However, in one sample, from Tesco, the level of positive DNA indicated horsemeat accounted for 29% relative to the beef content.
The FSAI said the retailers have agreed to remove all implicated batches from sale.
Professor Alan Reilly, chief executive of the FSAI, said while the findings posed no risk to health they did raise concerns. "The products we have identified as containing horse DNA and/or pig DNA do not pose any food safety risk and consumers should not be worried," he added. "Consumers who have purchased any of the implicated products can return them to their retailer.
"While there is a plausible explanation for the presence of pig DNA in these products, due to the fact that meat from different animals is processed in the same meat plants, there is no clear explanation at this time for the presence of horse DNA in products emanating from meat plants that do not use horsemeat in their production process."
He said it was not part of Irish culture to eat horsemeat: "We do not expect to find it in a burger; likewise, for some religious groups or people who abstain from eating pig meat, the presence of traces of pig DNA is unacceptable."
A spokeswoman for Tesco said the grocer was working with the authorities in Ireland and the UK, and with the suppliers concerned, to ensure that type of contamination did not happen again.
"We will not take any products from this site until the conclusion and satisfactory resolution of an investigation," she added. "The safety and quality of our food is of the highest importance to Tesco. We will not tolerate any compromise in the quality of the food we sell. The presence of illegal meat in our products is extremely serious."
Iceland said it had noted "with concern" the statement issued by the FSAI and had withdrawn from sale the two Iceland brand quarter-pounder burger lines implicated in the study, pending further investigation.
