Expert warns over horse DNA
Supermarkets and suppliers have also been frantically commissioning their own tests on meat products in a desperate attempt to find out the ingredients.
Campbell said there had been a rush on materials needed to do the lab analyses that can detect the wrong species in meat, with some supplies running out.
Tesco has admitted that criminality or gross negligence has almost certainly been involved in the adulteration of the economy beef burgers that were found to contain 29 per cent horse DNA by the Food Safety Authority of Ireland (FSAI) in test results published on Tuesday.
Ingredients and raw materials supplied by European processors to ABP are now the focus of efforts to determine how the adulteration took place.
ABP and a further company whose beef produce was found to contain horse DNA, Liffey Foods, supply several other major high street retailers. Beef products sold in Lidl and Iceland contained pork and horse DNA in the Irish tests and have been withdrawn from sale.
Asda, Sainsbury's and the Co-op used the same suppliers and have withdrawn lines as a precaution, although the FSAI did not test samples from these retailers because they do not have stores in Ireland.
Burger King also bought burgers from the same ABP Silvercrest factory in County Monaghan as Tesco but said it was confident that its products were made in a different way and were not contaminated.
ABP announced yesterday that it was shutting its Silvercrest factory following a further round of tests by the Irish agriculture department on samples collected this week in which most also contained traces of horse DNA.
The FSAI stood by its assessment that there was no risk to consumer health from the presence of horse and pig DNA in beefburgers. Any bacterial contamination would be killed by cooking, it said.
It also revealed that it had retested all the burgers that were positive for horse DNA to check for the presence of phenylbutazone, a commonly used medicine in horses that is not allowed in the food chain, and all of the results were negative.
A Food Standards Agency spokeswoman said: "The FSA is stressing that, on the basis of the evidence, there is no food safety risk to consumers from these products. There is nothing about horse meat that makes it any less safe than other meat products.
The meat products were supplied to the retailers by approved establishments. The burgers that contained horse DNA were tested by FSAI for the presence of phenylbutazone, a commonly used medicine in horses that is not allowed in the food chain; all of the results were negative."
The Environment, Food and Rural Affairs select committee announced on Friday that it would be summoning the minister and FSA to answer questions on 30 January about the effectiveness of UK checks on the food industry.