Food manufacturer Findus has confirmed results of tests carried out by Britain's Food Standards Agency that showed that some of the company's beef lasagne contained up to 100% horse meat.
Findus, a UK-based frozen food and seafood company which is behind brands including Young's and The Seafood Company, began a recall of its beef lasagne from retailers earlier in the week on advice from its French supplier, Comigel.
"Findus UK can confirm that testing of its beef lasagne, produced by a third-party supplier and not by Findus, has revealed some product containing horse meat," the company said in a statement.
The company said customers who had purchased the product should call or email its customer care helpline for a full refund.
Investigations into suppliers have been launched in recent weeks after revelations that beef products sold at major British supermarkets including Tesco and fast-food chain Burger King contained horse meat.
The meat content in Findus beef lasagne products tested positive for more than 60% horse meat, some were as high as 100%, the Food Standards Agency said in a statement.
The FSA said Findus tested 18 of its beef lasagne products and found 11 meals containing between 60% and 100% horsemeat.
"We have no evidence to suggest that this is a food safety risk," the FSA said, adding that it had ordered Findus to carry out further tests for a veterinary drug which was a risk to human health.
"The Findus beef lasagne was distributed to the main UK supermarkets and smaller convenience stores. Findus has already begun a full recall of these products.
"People who have bought any Findus beef lasagne products are advised not to eat them and return them to the shop they bought them from."
Findus said all its other products had been tested and were not affected.
"We understand this it is a very sensitive subject for consumers and we would like to reassure you we have reacted immediately. We do not believe this to be a food safety issue," Findus said in a statement.
"We are confident that we have fully resolved this supply chain issue. Fully compliant beef lasagne will be in stores again soon."