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".
More top news
MPs and peers have called for changes to the restrictions put in place during the coronavirus pandemic.
The emergency services are urging people going out to pubs, bars and restaurants this weekend to act responsibly.
Economy minister Diane Dodds is set to visit a number of hotels and eateries on Friday as they reopen their doors following pandemic restric