Prime Minister David Cameron has called the horsemeat scandal an "appalling situation", stressing that if criminal activity has taken place "there should be the full intervention of the law".
Speaking at Prime Minister's Questions, Mr Cameron said an enhanced testing regime not only found contamination, but discovered that in some instances horsemeat had been passed off as beef.
He called the discovery "completely unacceptable".
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The president said on Tuesday that he accepted the US intelligence community’s conclusion that the meddling took place.
The heir to the throne was interviewed for the show earlier in the year on his Highgrove Estate in Gloucestershire.