The Chosen By You fresh bolognese sauce withdrawn by Asda earlier this week has tested positive for 4.8% horse.

The sauce was initially withdrawn on a precautionary basis after preliminary DNA tests suggested it might contain equine DNA, but tonight (16 February) the company that makes the sauce – Ireland’s Greencore – said it had been informed by Asda that the meat content was 4.8% horse.

Greencore said it was carrying out a “thorough and comprehensive investigation” to find out how its supply chain had been compromised. “Greencore only sources products from customer and Greencore approved suppliers, which are regularly audited, and insists that they in turn use approved suppliers,” it said in a statement.

The meat supplier used by Greencore for the Asda sauce is ABP Food Group’s Nenagh plant in county Tipperary. Another ABP plant, Silvercrest Foods, made the Tesco Everyday Value burger that was found to contain 29.1% horse relative to the beef content.

On Friday, ABP Food Group confirmed it was a supplier to Greencore but strongly rejected it was to blame. “In the last few weeks we have carried out hundreds of tests on fresh beef and to date they have all tested negative for equine DNA,” the company said. “ABP reiterates again that we have never knowingly purchased or processed equine meat.”

Aside from the bolognese sauce, Asda has also withdrawn three other products made by Greencore as a precaution: a beef broth soup, a meat feast pasta sauce and a chilli con carne soup. But these had not come back positive for horse, Asda said in a blog posted on its website on Saturday.

“To date we have now carried out 197 tests on Asda brand beef products,” it added.  “The Bolognese Sauce is the only one of those 197 Asda products that has tested positive for the presence of horse DNA above the threshold set out by the Food Standards Agency (FSA).”

“Once again, we’d like to say how sorry we are if this situation has caused you any worry, upset or inconvenience. We are working hard alongside our suppliers to ensure you can have complete confidence in our food.

Greencore stressed that despite the withdrawals, it had “received assurance from Asda that it remains supportive of Greencore and the steps it is taking with regards to this matter”. It also said it was participating in an industry-wide testing programme, and that no other Greencore products had tested positive for horse to date.

On Monday (18 February), the company said it had carried out a precautionary deep-clean of its entire Bristol factory over the weekend, and had now resumed preduction.