Environment Secretary Owen Paterson has been criticised for his confused handling of the horse meat scandal after he ruled out an import ban – despite conceding that tainted foods could be "injurious to human health".
Ministers are facing calls to impose a moratorium on meat imports from the European Union amid concerns that the extent of the contamination of the British food chain is not fully understood.
Former Northern Ireland Secretary Mr Paterson, who is understood to have received a dressing down from Downing Street over a lethargic initial reaction to the presence of horse meat in processed food, has warned of more "bad results" this week from tests by retailers for further instances of contaminated beef.
A senior Conservative MP called for a moratorium on EU meat imports until the investigation into the origins of the horse meat – which on Sunday switched focus to Romania amid suggestions of links to organised crime – could be established.
Mr Paterson said no such ban could be considered under EU law until a risk to human health had been identified – only to admit that such a risk could take several more days to uncover.
Only beef products which have already been found to contain horse meat and withdrawn from sale by companies including Findus and Aldi are being tested for phenylbutazone or 'bute', a veterinary drug which is banned from the human food chain.
Speaking to LBC radio, Mr Paterson insisted there was currently "no evidence" of a health risk.
He said: "As we speak this is an issue of fraud and a conspiracy against the public, I think probably by criminal elements, to substitute a cheap material for that which was marked on the label.
"It is a labelling issue. Now we may find out as the week progresses and the tests begin to come in, we may find out there is a substance which is injurious to human health. We have no evidence of that at all at the moment."
The Food Standards Agency has asked retailers and local authorities to provide results by this Friday from tests for horse meat contamination on dozens of processed beef products.
Further analysis for bute, which can take a minimum of 48 hours, will be carried out only if horse meat has been found, meaning it could potentially be another week before any human health risk is established.
Tests for bute on Findus beef lasagne and similar products from Aldi, both which have been withdrawn after they were found to consist of up to 100% horse meat, are under way. Both the FSA and Mr Paterson have said it is safe to eat processed beef meals as long as they are not lines which have already been identified as containing horse meat.
Anne McIntosh MP, House of Commons food and rural affairs select committee chairwoman, 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."
Labour said a ban was not the answer, but shadow environment secretary Mary Creagh said: "What the Government hasn't done is get a grip, get the tests on the burgers that were withdrawn three weeks ago out. What they've done is sit on their hands and now they're behind the curve."
The horse meat scandal has spread all over the Continent as details of the elaborate supply chain in the meat industry emerge. French consumer safety authorities have said companies from Romania, Cyprus and the Netherlands as well as its own firms were involved. Romanian authorities have confirmed they are investigating while their Dutch counterparts said they are ready to do so if necessary. Beef products suspected of containing horse meat have also been withdrawn from shops in Ireland, Sweden and France.