(Corrects to show horse DNA not found in products supplied to Burger King)
Beef containing horse DNA that was supplied by an Irish company to major food companies like Tesco and Burger King originated in Poland, Ireland's agriculture department said on Saturday.
The British food industry has been rocked by the revelation retailers sold beef products that contained horse DNA, a scandal that has also left Ireland's 2 billion euros (1.6 billion pounds) beef industry reeling from the knock-on effects.
Results of tests showed that Polish ingredients used by Irish burger manufacturer Silvercrest contained 4.1 percent horse DNA, the agriculture department in a statement.
It said tests on samples taken from Irish food ingredients were negative for equine DNA and agriculture minister Simon Coveney said the results maintained the integrity of Irish food production.
Burger King, one of the most popular fast-food chains in Britain and Ireland, said on Thursday it had stopped using Silvercrest's products. There was no horse DNA found in products sold by Burger King.
Smaller retail chains Aldi, Lidl and Iceland have also sold beef products found to contain horse DNA.
Silvercrest's parent company ABP Foods reiterated the plant had never knowingly sold equine products and that it would appoint a new management team, independently audit third party suppliers and source all future raw material from Britain and Ireland.
Tesco, which withdrew from sale all products supplied by Silvercrest, said in a statement that the source of horse DNA identified by the department correlated with the results of its own investigations at the plant.
Food safety experts say horse DNA poses no added health risks to consumers, but the discovery has raised concerns about the food supply chain and the ability to trace meat ingredients.
(Reporting by Padraic Halpin; Editing by Jason Webb)