Environment secretary Owen Paterson will hold an emergency meeting on Saturday with the Food Standards Agency (FSA) and retailers, as ministers warned of a "criminal conspiracy" at the heart of the horse meat scandal.
Frozen food company Findus UK has reiterated its apology after tests found up to 100% horse meat in some of its beef lasagnes, while claims emerged that the meals may have been contaminated since August.
The meeting comes after Paterson told Sky News he would be perfectly happy to eat a frozen ready-meal lasagne for his Friday night dinner - saying the issue was the mislabelling and not the safety of the food.
This week, supermarket chain Aldi confirmed that two of its ready meal ranges produced by Comigel, the French supplier also used by Findus, were found to contain between 30% and 100% horse meat.
And last night, the scandal became a police matter as Scotland Yard announced they had met representatives from the FSA.
Prime Minister David Cameron said it was "shocking" and "completely unacceptable", as the FSA ordered firms to carry out tests on all processed beef foods.
The Trading Standards Institute said the discovery of such high levels of horse meat suggested "deliberate fraudulent activity".
Some Findus lasagnes were revealed to be almost entirely horse meat
Scotland Yard said officers had met the FSA over the scandal, although there is currently no official police investigation.
Paterson said he wanted to discuss in detail how the current system works and at which stages of the food manufacture process testing goes on when he attends today's meeting.
He told BBC News: "People are absolutely right to want to know that if they buy a product marked processed beef it contains processed beef, not processed horse.
"I'm very proud of the British farming industry, the traceability through the system, the rigorous production systems in our own industry, and I do not want to have any slur cast on them."
Responding to fears that school dinners might be contaminated with horsemeat, the Department for Education said schools and councils were responsible for their food contracts.
A spokeswoman for the Local Authority Caterers Association (Laca) said: "We are as sure as we can be that this is not affecting the school catering area."
She added that there were "strict guidelines" around food safety and supplying dinners in schools, including transparency and traceability of ingredient provenance, written into contracts.
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