Opposition TDs (members of Parliament) are trying to establish why the Irish government only revealed the presence of horse meat in beef burgers last week although officials had known about it for at least four weeks.

While 10 million beef burgers were withdrawn from the market in Ireland and Britain when the alert was made public, Agriculture Minister Simon Coveney defended the delay.

Coveney said there had been no food safety risk and that there had been a need to carry out further testing.

“If you get a result like this, and there’s no danger to human health, which there isn’t, but if there is a significant reputational threat to an industry, you have to make sure those results are accurate,” Coveney said.

The Agriculture Department was contacted by the Food Safety Authority of Ireland on December 21 after it got early test results in November.

While the government and several agencies have specified there was no threat to health – although one series of tests showed 29.1 percent horse meat in a burger in the Tesco supermarket chain – Bord Bia, which markets Irish food to the world, was called in to help repair the damage to the international reputation of Ireland’s 3 billion food industry, which employs 100,000 people.

Food Safety Authority of Ireland confirmed it received initial findings about the presence of horse meat in beef burgers at the end of November, but director of consumer protection Ray Ellard insisted it was crucial to get laboratory verification before making a public announcement.

Initial inquiries have indicated that the source of supply of extra protein additive in the burgers was the Netherlands and Spain.

Coveney has said there was “no evidence so far” to show the two Irish processing plants that produced the burgers, Liffey Meats in Cavan and Silvercrest Foods in Monaghan, had knowingly brought in horse meat to use in their burgers.

Beef magnate Larry Goodman, owner of Silvercrest, said his processing company is not to blame.  He questioned the validity of the DNA testing that found traces of horse and pig DNA in his beef burgers.

Goodman said the company had never bought or traded in horse meat, and he suspected the contamination came from a hamburger filler product sourced from a supplier on the continent.  

Taoiseach (Prime Minister) Enda Kenny said on The Week in Politics program on RTE television that he was “not satisfied” the government had got to the bottom of how horse meat ended up in beef burgers.

“I am not satisfied that we’ve come to the end of this yet. There’s a process in train here, these are very forensic tests,” he said.

“I’ve seen different reports now in respect of this issue which is a matter of reputation for our country. We’ve gained enormous respect internationally for the exceptionally high standards that we have here. That’s why these things were discovered in the first place.”

After further laboratory tests last week at two plants the Department of Agriculture on Monday night said samples at one company, Liffey Meats, had come back clear. There was no presence of horse DNA in the product manufactured between January 10 and January 16.

The Department said more tests will be needed at Silvercrest after further samples were also taken there.