Criminal prosecutions could be brought following the discovery of horse meat in some supermarket beef burgers, the Government has said.

Environment minister David Heath said standards were generally very high in the British food industry and backed the Food Standards Agency's (FSA) risk-based checking system.

Answering an urgent question from Labour's shadow environment secretary Mary Creagh in the Commons, Mr Heath acknowledged the seriousness of the discovery. He said: "It is very important neither you, nor anyone else in this House, talks down the British food industry at a time when the standards in that industry are of a very high level.

"Because something has been discovered in Ireland, which is serious, which may lead to criminal proceedings, does not undermine the very serious efforts which are taken by retailers, by processors and by producers in this country to ensure traceability and ensure standards of food that are available to consumers."

In his remarks, Mr Heath reported to the Commons about the situation, which saw DNA testing in Ireland reveal the presence of horse meat and pig meat in some supermarket beef burgers. In one case, testing revealed up to 29% of a Tesco burger was horse meat. The retail giant has now taken out adverts in national newspapers apologising to customers.

Raising her urgent question, Ms Creagh said there was "understandable" public anger about supermarkets selling food which was not properly labelled. She said: "Consumers who avoid pork for religious reasons will be upset they may have unwittingly eaten it and eating horse is strongly culturally taboo in the United Kingdom. It's not illegal to sell horse meat but it is illegal not to label it correctly.

"Customers must have the confidence the food they buy is correctly labelled, legal and safe. The UK is part of a global food supply chain. The food industry lobbies vigorously for a light-touch regulation system from Government. Testing, tracking and tracing ingredients is expensive but not testing will cost retailers, processors, British farmers and consumers much more."

Ms Creagh raised questions about the responsibility for food labelling, which she said the Government split between the FSA, the Department of Health and the Department for Environment, Food and Rural Affairs. She urged the Government to consider introducing DNA testing of meat products, the system which detected the problem in Ireland. And she suggested the loss of 700 trading standards officers could have made the "fraud" "more widespread and less likely to be detected".

Mr Heath replied: "You are right to say consumers have a right to expect the food they eat is what it says on the label. This is a very serious breach of that principle in the cases that were picked up in Ireland. That is why we are taking the measures we are taking. Where you are completely wrong is in what you are saying about responsibility for labelling. Let us be absolutely clear: the responsibility for policy of labelling goes with the most appropriate department. But the responsibility for checking the content of food lies with the FSA and only the FSA."

Challenged on why the horse contamination was discovered in Ireland rather than by UK authorities, Mr Heath said: "This is a European trade. The meat in question almost certainly did not come from the UK, it came from a third country to be processed in Ireland. It is not surprising, therefore, that UK authorities would not have picked that up. But we are investigating very fully and there may well be criminal prosecutions as a consequence."