France and Britain called on Monday for the "criminals" who disguised horsemeat as beef to be tracked down, as Romania angrily denied it was to blame for the frozen food scandal spreading across Europe.
Britain's food minister Owen Paterson said an "extensive" criminal conspiracy could be behind the scandal and said he believed warnings had been sent out to 16 different countries that might be affected.
"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."
French President Francois Hollande said there had been "unacceptable behaviour, and sanctions must be pronounced" against those responsible. He also said that his advice to the French was to eat only meat from France.
Supermarket chains in Britain, France and Sweden have pulled millions of packs of lasagne, other pasta dishes, shepherd's pies and moussaka after it emerged that frozen food companies had used horsemeat instead of beef.
British supermarkets were the first to pull the products last week after French firm Comigel warned that the beef it supplied to Findus frozen food firm -- which sold its ready-to-eat meals to supermarkets -- was suspect.
Comigel said it got its meat from another French firm, Spanghero, which said it was supplied from two abattoirs in Romania who allegedly passed horsemeat off as beef.
But Romanian Prime Minister Victor Ponta on Monday angrily denied his country was to blame.
"We have made verifications... There exists no violation of European rules and standards" by the two abattoirs, Ponta told reporters, while his agriculture minister said there had been no false labelling of meat at the two abattoirs.
Ponta said Spanghero "did not have a direct contract with Romanian firms" and he called on European Union officials to find out who was to blame.
"Romania cannot accept to be the usual suspect," he said. "I am very angry, to be very honest."
French ministers prepared to hold a crisis meeting with key players in the meat industry later Monday, as French anti-fraud agents searched the premises of both Comigel and Spanghero.
Both these firms have denied any wrongdoing and said they will sue suppliers who duped them.
French Agriculture Minister Stephane Le Foll warned that more trouble lay ahead if Europe's complex system of wholesale meat trading was not reformed to make it simpler to trace the origin of food.
"We have to get out of this fog, because we can go on calling for traceability...but if the system is so murky, if the fog is so thick that we are all lost, then we will end up with big problems," he told RTL radio.
The head of France's ANIA food industry association, Jean-Rene Buisson, who was due to attend the crisis talks with the government, insisted that his country's regulatory system was "the best in the world".
"We are not responsible for the fraud of one of our suppliers," he told Europe 1 radio.
"The traceability of food products is not being called into question in this affair. We put in place the best system in the world after the 'mad cow' crisis which will enable us to find out in two or three days who is responsible," he said.
The French government has promised the results of an urgent inquiry into the scandal by Wednesday.
Findus has said it will file a legal complaint in France after evidence showed the presence of horsemeat in its supply chain "was not accidental".
Its Nordic branch said it planned to sue Comigel, which sells its products to customers in 16 countries, and its suppliers.
In Britain, tests have found that some frozen ready meals produced in mainland Europe and labelled as processed beef actually contained up to 100 percent horsemeat.
But the country's food minister dismissed calls for a ban on EU meat imports, describing the idea as a "panic measure".
The scandal has had particular resonance in Britain, where eating horsemeat is considered taboo. British authorities have also said they are testing to see whether the horsemeat contains a veterinary drug that can be dangerous to humans.