French anti-fraud agents have searched two firms at the centre of a scandal over horsemeat disguised as beef in ready-to-eat frozen meals sold in supermarkets across Europe.
The inspections on Monday came as French ministers prepared to hold a crisis meeting with key players in the meat industry, as the scandal that erupted in Britain continued to spread across the continent.
The DGCCRF fraud office said its inspectors were in the Comigel plant in the northeastern city of Metz and on the premises of Spanghero, which is based in the southwest.
Supermarket chains in Britain, France and Sweden have begun pulling 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 Comigel warned that the beef it supplied to Findus frozen food firm - which sold its ready-to-eat meals to supermarkets - was suspect.
Comigel, which got its meat from Spanghero, said it had been cheated by its suppliers, while Spanghero in turn said it had been duped by abattoirs in Romania.
Both firms said they will sue suppliers, and the French and British governments have vowed to punish those who sold horsemeat purporting to be beef.
French Agriculture Minister Stephane Le Foll warned on Monday 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.
"There are people who are out to defraud, who are trying to cheat," said Le Foll, who was due to meet later Monday for emergency talks with Consumer Affairs Minister Benoit Hamon and meat industry leaders.
The meat used in these products has been traced from France through Cyprus and The Netherlands to Romanian abattoirs.
The head of France's ANIA food industry association, Jean-Rene Buisson, who was due to attend the talks with the government, insisted Monday 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.
Officials in Bucharest announced on Saturday their own inquiry after it emerged that abattoirs there allegedly produced the horsemeat sold on as beef.
Findus has said it will file a legal complaint in France on Monday after evidence showed the presence of horsemeat in its supply chain "was not accidental".
Its Nordic branch said on Sunday it planned to sue Comigel, which sells its products to customers in 16 countries, and its suppliers.
Comigel head Erick Lehagre told AFP the company had been fooled by its suppliers and vowed to seek compensation.
In Britain, tests have found that some frozen ready meals produced in mainland Europe and labelled as processed beef actually contained up to 100 per cent horsemeat.
But Food Minister Owen Paterson 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.