Tesco (Other OTC: TSCDY - news) is introducing DNA testing across its meat products and has dropped its frozen burger supplier after burgers containing horse meat were found on sale in its supermarkets.
Tesco said on Wednesday that it had been "working hard to understand" why traces of horse DNA were found in burgers on sale in some of its supermarkets two weeks ago.
The company pledged to stop such an event "ever happening again" and plans to introduce a comprehensive system of DNA testing across its meat products.
Tim Smith, Tesco's technical director, said: "We now understand - with as much certainty as possible what happened. The evidence tells us that our frozen burger supplier, Silvercrest, used meat in our products that did not come from the list of approved suppliers we gave them.
"Nor was the meat from the UK or Ireland (OTC BB: IRLD - news) , despite our instruction that only beef from the UK and Ireland should be used in our frozen beef burgers. Consequently we have decided not to take products from that supplier in future. We took that decision with regret but the breach of trust is simply too great."
Scientific tests carried out by the Food Safety Authority of Ireland found traces of horse DNA in burgers on sale in some of the UK and Ireland's leading supermarkets, including Tesco, Lidl, Aldi, Iceland and Dunnes Stores.
Supermarkets have pulled tens of thousands of frozen beefburgers from their shelves after tests revealed that products from Irish supply company Silvercrest contained horse and pig DNA. Tesco was first to remove the products.
Silvercrest, an Irish company, sold beef burgers to Tesco containing 29 per cent horse meat. Silvercrest said earlier this month that it had "done nothing wrong" . It believed the contaminated meat was from Europe and is investigating two suppliers.
"It has shown that, in spite of our stringent tests, checks and controls there remained a small possibility that something could go wrong and it did," said Mr Smith.
"We want to stop it ever happening again, so we are taking action to reduce that possibility still further."
"To underpin the strong measures already in place, we will now introduce a comprehensive system of DNA testing across our meat products. This will identify any deviation from our high standards," he added.
"These checks will set a new standard. It will be a significant investment for Tesco, borne by Tesco. We want to leave customers in no doubt that we will do whatever it takes to ensure the quality of their food and that the food they buy is exactly what the label says it is."