Findus UK has withdrawn from sale or destroyed about 380,000 of its frozen beef lasagnes, after the meat content of some was found to be 100% horse instead of beef.

About 180,000 of the products had to be taken off shelves, with a further 200,000 destroyed in warehouses.

The company said it pulled the lasagne – in 320g, 360g and 500g sizes – after the French manufacturer of the product, Comigel, flagged up a problem with the line.

Findus initially described this as a “labelling” problem, but admitted yesterday that the problem was, in fact, adulteration with horse meat. The Food Standards Agency subsequently said tests on Findus lasagne showed the meat content was between 60% and 100% horse.

The FSA said it had not received any evidence so far that the horse meat posed a safety risk, but it has ordered Findus to tests the lasagne for bute, a commonly used veterinary medicine, which can be harmful to humans and is therefore not allowed in the food chain.

The FSA also said it now wanted the industry to test more widely for possible horse meat contamination, with all processed beef products – such as meatballs, lasagnes and burgers – to be subjected to tests. It has set a deadline of 15 February for the industry to submit its results to the FSA.

Findus UK said: “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.We are confident that we have fully resolved this supply chain issue. Fully compliant beef lasagne will be in stores again soon.”