Tesco has cleared its shelves of beef burgers following the fallout over horsemeat contamination, and investigations are under way to work out how it happened.

Two months ago tests by Irish food safety officials found that some burgers contained horse DNA - in one sample the meat accounted for 29 per cent of the content.

Although those who carried out the tests said there was no risk to human health, there has been public outcry over the issue.

"For some religious groups, or people who abstain from eating pig meat, the presence of traces of pig DNA is unacceptable”  FSAI chief executive Professor Allan Reilly told the BBC.

From the BBC report [2]:

FSAI chief executive Prof Alan Reilly said there was "a plausible explanation for the presence of pig DNA in these products, due to the fact that meat from different animals is processed in the same meat plants".

But he added: "There is no clear explanation at this time for the presence of horse DNA in products emanating from meat plants that do not use horsemeat in their production process.

"In Ireland, it is not in our culture to eat horsemeat and, therefore, we do not expect to find it in a burger."