Horsemeat in the food chain could have been passed off as beef for three years, the country’s food safety watchdog has said.

Alan Reilly of the Food Safety Authority of Ireland said he suspects the rogue product may have been in beef for years.

The first definitive test showing horsemeat contamination only came in April last year, but Prof Reilly insisted the problem was right under the noses of Europe’s food safety watchdogs.

Prof Reilly said the authority had been using DNA testing on meat since 2005, but decided seven years later to see if people were “cheating” by passing off horsemeat for more expensive cuts.

He admitted he had “lost some sleep” after one burger was found to contain 29% horsemeat.

The FSAI boss revealed the decision to go public on the fraud was very difficult.

He added: “The Irish media attacked us for going public, but what we uncovered was a massive international fraud.”

Prof Reilly said the scandal has removed trust from buyers but he cannot see the situation happening again.

He added: “The industry norm now is to buy nothing on trust and to test it. So I couldn’t see it happening again.”

The FSAI tested several blocks of frozen meat used for burgers.

Prof Reilly said in one case a block labelled as Polish beef trim contained “horsemeat with an Irish stamp and a micro-chip for a Polish horse.”