The Food Safety Authority of Ireland said the meat came from two processing plants in Ireland and one in Britain and was then sold in supermarkets including Tesco, Dunnes, Aldi, Lidl and Iceland, the BBC reported.
The FSAI said in a statement that 27 beef burger products were analyzed and 10 tested positive for horse DNA and 23 tested positive for pig DNA.
It also examined 31 beef meal products, such as cottage pie, beef curry pie and lasagna, and found 21 contained pig DNA. No traces of horse DNA were found.
FSAI chief executive Alan Reilly said in a statement:
“Whilst there is 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, 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. Likewise, for some religious groups or people who abstain from eating pig meat, the presence of traces of pig DNA is unacceptable.
"We are working with the meat processing plants the Department of Agriculture, Fisheries and the Marine to find out how horse DNA could have found its way into these products.”
The Independent reported that while there was no risk to human health, retailers were removing the implicated batches of burgers.