Irish authorities believe that "filler product" found in contaminated burgers came from Poland and was a mixture of beef and horse offcuts, the Food Standards Agency (FSA) has said.
The contaminated beef, which was sold in supermarkets, was in the form of blocks of frozen product from a Polish supplier that had been used for a year.
Investigations are going on into how long contaminated meat might have been in use, FSA chief executive Catherine Brown told the Commons Environment Committee.
More top news
Which? said Amazon and eBay had removed the alarms that failed to sound in test conditions.
Economists worry about a trade war between the United States and its most vital trading partners.
During their visit, Charles and Camilla will meet local businesses and people in the city centre before joining a reception in the Guildhall