Burger King has admitted that some burgers made in the plant of one of its processors in Ireland were tainted with horse meat, but that the meat never reached its restaurants, The Guardian reported.

"Four samples recently taken from the Silvercrest plant have shown the presence of very small trace levels of equine DNA. This product was never sold to our restaurants," the company said in a statement on Thursday.

"They promised to deliver 100 percent British and Irish beef patties and have not done so. This is a clear violation of our specifications, and we have terminated our relationship with them."

Burger King had originally stressed that its patties are made with 100 percent beef, although it later dropped Silvercrest, the food processing plant that received meat from the Polish distributor. Burger King said that the meat did not did make its way to the firm's restaurants.

"While the Food Safety Authority of Ireland has stated that this is not a food safety issue, we are deeply troubled by the findings," said Diego Beamonte, Burger King's vice president of global quality.

Last month, Burger King said that its patties were made from 100% beef following the revelation that the British supermarket chain Tesco had sold burgers that were discovered to contain traces of horse meat.

Meanwhile, food safety experts say horse meat poses no added health risks to consumers, but the discovery is disconcerting and left consumers wary of what is really in their hamburgers.

Tesco, one of the world's largest food retailers and known in the U.S. under its Fresh & Easy brand, apologized for the horse meat-laden burger and pulled store brand burgers from groceries in Britain and Ireland.

The DNA tests found horse in the following products: Tesco Everyday Value Beef Burgers 29.1%; Tesco Beef Quarter Pounders 0.1%; Oakhurst Beef Burgers in Aldi 0.3%; Moordale Quarter Pounders in Lidl 0.1%; Flamehouse Chargrilled Quarter Pounders in Dunnes Stores 0.1%; two varieties of Iceland Quarter Pounders 0.1%.