The UK food watchdog is considering whether legal action should be taken against companies at the centre of the scandal over horsemeat found in beef burgers.
The Food Standards Agency (FSA) said it would consult relevant local authorities and the Food Safety Authority of Ireland (FSAI) before making a decision to take action.
After a meeting with food industry representatives, the FSA said it would continue a review of the traceability of the food products identified in an FSAI survey which uncovered the scandal.
The FSA said it would try to further understand how the contamination took place and help to carry out a UK-wide study of food authenticity in meat products.
Environment minister David Heath told the Commons standards were generally very high in the British food industry and backed the FSA's risk-based checking system.
He told Labour shadow environment secretary Mary Creagh: "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.
But Ms Creagh said there was "understandable" public anger and added: "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.
"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 also raised questions about the responsibility for food labelling, which she said the Government split between the FSA, the Department for Health and the Department for Environment, Food and Rural Affairs (Defra).
An FSA spokesperson told Sky News: "Defra is the policy lead on areas such as food authenticity, food composition, labelling. But if food is found to not be fulfilling the requirements on these issues, the FSA would take action and investigate."
Meanwhile Tim Lang, professor of food policy at City University in London, warned horse meat could have been in beef burgers for years but remained undetected because of insufficient food regulation.
He blamed the findings on light industry regulations, tweeting: "Horse meat in beef burgers suggests failings in corporate food governance.
"Law clear - 'food shall be of nature, substance and quality demanded'."
Tesco placed full-page adverts in a number of national newspapers apologising to customers and has also promised to refund those who bought the contaminated products.
In the advertisement, entitled "We apologise", the supermarket said: "While the FSAI has said that the products pose no risk to public health, we appreciate that, like us, our customers will find this absolutely unacceptable ... We and our supplier have let you down and we apologise."
The food company at the centre of the scandal - ABP Food Group - vowed to adopt strict DNA testing of its products to prevent a repeat.
The company, one of Europe's biggest suppliers and processors, is being investigated by health and agriculture authorities in the UK and Ireland (OTC BB: IRLD - news) and it also sent operatives to Continental (Stuttgart: 879538 - news) suppliers to make unannounced visits.
Two of its subsidiaries - Silvercrest Foods in Ireland and Dalepak Hambleton in Yorkshire - supplied beef burgers with traces of equine DNA to supermarkets, including the product classed as 29% horse.
An ABP spokeswoman said: "It is vital that the integrity of the supply chain is assured and we are committed to restoring consumer confidence.
A third company, Liffey meats, based in Co Cavan, Ireland, was also found to be supplying products to supermarkets with traces of horse DNA.
Suppliers in the Netherlands and Spain have been identified as the possible sources for incorrectly labelled ingredients.
The results of the FSAI survey, verified in laboratories in Germany, showed low levels of horse in beef products sold in Tesco, Lidl, Aldi, Iceland and Dunnes Stores in Ireland.
Some burgers were also being sold in the UK but retailers insisted all suspect brands had been taken off the shelves within hours of the findings being released on Tuesday evening.
The scandal saw nearly 1% - or roughly £300m - wiped off the value of supermarket Tesco on Wednesday. Shares recovered slightly on Thursday.
Prime Minister David Cameron said supermarkets had to take responsibility for what he said was an extremely disturbing case.
The FSAI analysed 27 beef burger products with best before dates from last June to March 2014 with 10 of the 27 products - 37% - testing positive for horse DNA and 85% testing positive for pig DNA.
The tests found horse DNA in the following products: Tesco Everyday Value Beef Burgers 29.1%, Tesco Beef Quarter Pounders 0.1%, Oakhurst Beef Burgers in Aldi 0.3%, Moordale Quarter Pounders in Lidl 0.1%, Flamehouse Chargrilled Quarter Pounders in Dunnes Stores 0.1%, and two varieties of Iceland Quarter Pounders 0.1%.
Ten million burgers have been taken off shelves as a result of the scandal.
Liffey Meats said it believed horse DNA was originally contained in raw ingredient marked "bovine only", supplied by an EU approved factory and were minute traces.
In a statement, the company said: "Liffey Meats has never produced, purchased or traded any equine products."
:: The FSAI operates an advice line on 1890 33 66 77 from 9am-5pm, and in the UK the FSA general help line is 020 7276 8829.
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