Horse meat was found in popular UK super market chain Tesco's beef burgers.

"People in our country will have been very concerned to read this morning that when they thought they were buying beef burgers they were buying something that had horse meat in it," said Prime Minister David Cameron in Parliament according to Reuters."This is a completely unacceptable state of affairs."

The Associated Press reported that the beef burgers also had traces of pig DNA in the burger products. Authorities are saying the burgers were made of approximately 30 percent horse meat.

Simon Coneney who is Ireland's Agriculture Minister said that a meat processor in County Monaghan which is on the border with Northern Ireland was to blame, the AP reported. He said to broadcaster RTE that an additive in the burger had horse meat in it.

The additive was "either falsely labeled, or somebody made a mistake, or somebody was behaving recklessly. That allowed some horsemeat product to come into the system that shouldn't have been here," he said according to the AP."A mistake has been made here, it has been flagged by our systems as it should have been, and we will take the appropriate action to ensure it doesn't happen again."

Tesco PLC has apologized for the horse meat incident and said that it was going to pull the burgers from store shelves in Ireland and Britain.

"The presence of illegal meat in our products is extremely serious," the company said in a statement according to the AP."Our customers have the right to expect that food they buy is produced to the highest standards. ... We understand that many of our customers will be concerned by this news, and we apologize sincerely for any distress."