The horse meat scandal is the result of a criminal fraud conspiracy, the government has said.
Owen Paterson, the Environment Secretary, said the abuse of the food industry could have been on an "extensive" scale throughout Europe.
His comments come as pressure mounts for a ban on meat imports until the crisis has been averted.
Owen Paterson will address MPs on the horse meat scandal
Paterson, who will address MPs on the scandal on Monday, has admitted the horse meat could turn out to be harmful to humans.
But he insisted: "At the moment, all the evidence is that these products are entirely safe."
Meanwhile, concerns have been raised about poor levels of food hygiene when meat is transported.
And legal actions are expected as companies try to cope with the fallout from the scandal.
Findus lasagne contained up to 100% horse
Companies form Romania, Cyprus and the Netherlands are thought to be involved, with warnings issued to 16 countries.
One theory for the apparent increase in the presence of horse meat in the food chain is new restrictions on using horses on roads in Romania, which have led to a surge in numbers of animals being put down.
Paterson said: "Reports today we have had from France looks as though it might have been pinned down to two abattoirs in Romania but I will be talking to authorities later in the day to establish that.
"I very much hope that these legal processes do flush out the criminals because it is completely unacceptable that British consumers should be sold a product marked as one thing which actually contains something else."
Speaking on BBC Breakfast, he added: "This is a case of fraud and a conspiracy against the public, this is a criminal action, substituting one material for another.
"If a British consumer goes into a retail store and buys a beef product, they should expect to get beef in that product, not horse.
"So this is a straight case of fraud and I think you will see legal actions beginning in certain continental countries today.
"I will be taking it up with certain ministers and also with the Commission in Europe, because this is overall a European Commission competence.
"It is absolutely unacceptable that consumers are being passed off with one product when they buy another."
The chair of the Environment, Food and Rural Affairs select committee, Conservative MP Anne McIntosh said: "I believe there should be a moratorium on the movement of all meat until such time as we can trace the source of contamination."
But shadow environment secretary Mary Creagh said banning meat imports was a "knee-jerk reaction".
The Food Standards Agency has said there is no evidence to suggest the horse meat detected in beef products poses a danger to humans, but confirmed that tests have been ordered for the veterinary drug phenylbutazone as animals treated with "bute" are not allowed to enter the food chain.
Frozen foods firm Findus, which has taken its beef lasagnes made by French food supplier Comigel off shelves after some were found to have up to 100% horse meat in them, said it was considering taking legal action against its suppliers as an internal investigation "strongly suggests" that the contamination "was not accidental".