Fraud investigations linked to the horse meat scandal are pointing towards Europe, the head of food standards in Northern Ireland said.
Labour's claim that 70,000 horses had disappeared from Northern Ireland in recent times and possibly ended up in food were not recognised by a senior government vet during a committee meeting at Stormont.
Robert Huey, deputy chief veterinary officer in Northern Ireland, said: "I do not know what the basis of it is."
Gerry McCurdy, director of the Food Standards Agency (FSA) in Northern Ireland, said the investigation into the source of the fraud still had some way to go but added differences in the cost of beef and horse offered an incentive for wrongdoing.
"If you are selling horse meat, someone said for £700 a tonne versus £3,000 a tonne, for anyone who is in the game of being fraudulent there is an extremely helpful financial incentive there for them to break down product," he said.
Two Stormont committees held a special meeting to debate the issue of contaminated meat. Assembly members also questioned Department of Agriculture and environmental health officials.
Elements of a consignment of meat at Newry firm Freeza Meats was found to contain about 80% horse meat.
Sue Ramsey MLA said: "Public confidence has been shattered."
Mr McCurdy said there was more demand for cheaper processed meat.
"The local beef is probably too expensive for those burgers. That still does not excuse supermarkets from ensuring that food is not safe, simply because it is the low end of the market in that sense should still not prejudice consumers," he added.