Fresh tests at suppliers in the UK and Ireland affected by the horse meat in beef burgers scandal have come back clear, but officials are still trying to track down the source of the problem.

The UK Food Standards Agency said late today (25 January) that all seven samples of meat it took from the Dalepak plant in northern England came back negative for horse and pig DNA.

Tests earlier this week by the Food Safety Authority of Ireland (FSAI) also found no new cases of horse DNA in products at the Silvercrest plant in the country.

Both facilities were among those named in the FSAI's initial announcement last week that it had found horse and pig DNA in beef burgers and ready meals on sale in the UK and Ireland; prompting recalls by Tesco, Aldi, Lidl, Iceland and Dunne Foods, as well as "precautionary" recalls from retailers using the same suppliers, including Sainsbury's, Asda and Waitrose.

News of the negative tests will be used to show that officials and the food industry have managed to isolate the problem.

However, there remains a lot of uncertainty. Laboratories have been working over-time this week to help retailers and foodservice clients to test products, while the FSA is committed to testing a wide range of meat in the UK.

In addition, the source of the horse and pig DNA has yet to be confirmed. Food safety authorities in Spain and the Netherlands have been helping the FSA and FSAI to check on local ingredients suppliers, but no company has been named publicly.

"I am not prepared to draw any conclusion until I’m fully satisfied that such conclusions are supported by facts,” said Ireland's agriculture minister, Simon Coveney, today. The FSAI and Irish ministry have yet to analyse further tests.