Tesco and the Co-operative Group have both terminated their respective burger contracts with Silvercrest, the Co Monaghan company at the centre of the recent horse meat in burgers controversy.
The Co-op Group, which is the UK's fifth largest food retailer, said it was ending its contract with Silvercrest after carrying out its own tests on the frozen burgers.
In a statement the group said it specifies that all meat in its frozen burgers should be 100% British, which it did not believe was the case with some of those supplied by Silvercrest.
Silvercrest is owned by Larry Goodman's ABP group.
In a statement, the Tesco group said it made the decision to drop its €15m burger contract with regret, but that the breach of trust had been too great.
It also said it remains committed to the Irish food and drink industry and will continue to be the largest buyer of Irish food in the world.
"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, despite our instruction that only beef from the UK and Ireland should be used in our frozen beef burgers,'' Tesco said.
The statement said that ultimately Tesco is responsible for the food it sells, so it is not enough just to stop using the supplier. To this end, the UK retailer is now introducing a comprehensive system of DNA testing across its meat products.
Responding to Tesco's decision ABP Food Group CEO Paul Finnerty said the company had "learnt important lessons from this incident" and was determined to ensure it would not happen again.
The company said it had implemented complete management change at Silvercrest and was putting new procedures in place to better audit its suppliers.
The company also welcomed Tesco's decision to continue to purchase fresh Irish beef worth over €100m a year from other ABP companies.
In the Irish market since the late 1990s, Tesco has grown to become the leading grocery retailer in country with 139 stores.
In a statement, Tesco Ireland's chief executive Tony Keohane said the company buys Irish food and drink worth €2 billion a year, with €700m of this exported to Tesco stores internationally.
He noted that Tesco's international purchases account for approximately 8% of total food and drink exports from Ireland.
''Our buying of Irish beef amounts to €177m a year and will continue. The change in our buying relates only to frozen burgers from the Silvercrest plant which is valued at about €15m a year,'' Mr Keohane said.
Tesco said it plans to open discussions with other Irish beef processors in relation to the sourcing of frozen burgers in the near future.