The beleaguered minister at the centre of the horsemeat scandal, Owen Paterson, has asked the Food Standards Agency to investigate claims that the government was warned potentially harmful horsemeat could enter the food chain two years ago.
The environment secretary ordered the investigation after it was reported the government was warned in 2011 that horsemeat with possible drug residue was getting into food and that the situation could blow up into a scandal.
"I have discussed it with the chief executive of the FSA this morning and she is going to go back through the records and see exactly what was said at the time," Paterson told Sky News's Murnaghan programme.
John Young, a former manager at the Meat Hygiene Service, now part of the Food Standards Agency (FSA), told the Sunday Times he helped draft a letter to the Department for Environment, Food and Rural Affairs (Defra) in April that year that he said was ignored.
The letter to former minister Sir Jim Paice on behalf of Britain's largest horsemeat exporter, High Peak Meat Exports, warned the government that its passport scheme, designed to stop meat containing the anti-inflammatory drug phenylbutazone, known as bute, getting into the food chain was a "debacle".
"Defra gave nearly 80 organisations the authority to produce passports and some of them are little better than children could produce … It's a complete mess," he said.
Paice said he did not remember seeing the warnings, telling the Sunday Times: "If this information was in Defra and was not being acted upon, it warrants further investigation. I would like to know why on earth I was not being told about it."
Defra claimed on Sunday that the horse passports issue was "unrelated to the fact that horsemeat has been fraudulently passed off as beef."
The latest development follows news that rogue horsemeat had been found in meals destined for hospitals and schools. In Lancashire, cottage pies for 47 schools across the county were withdrawn after testing positive for horsemeat. It was not clear how long the contaminated food had been on the menu or how many pupils may have eaten it.