Burgers containing horse meat could have been made from diseased or injured animals, according to environmental health experts.
Health concerns have been raised by the Society of Chief Officers of Environmental Health in Scotland (SOCOEHS) over the safety of beefburgers which have been found to contain horse meat. The chief of the SOCOEHS said "there is no way of telling whether the meat is safe" because these burgers have bypassed official inspection.
John Sleith, chairman of the organisation, said: "We note that statements are being made that it is not a health issue, but our concern is there is no information on how the horse meat came to be in the burgers and so there is no way of telling whether the meat is safe to eat. It could be from diseased or injured animals, for example.
"Investigations are being carried out in the Irish Republic on exactly how these burgers were made."
Mr Sleith also said this scandal was an example of "food fraud", which is becoming an increasing problem.
"This episode is indicative of a growing trend we are finding, where there is substitution of meat products," he said. "Recently, for example, there have been cases of cheap beef being sold as more expensive lamb in curries."
Tesco has apologised to customers for selling beefburgers containing horse meat.
Aldi, Lidl and Iceland have also withdrawn frozen beefburgers from their shelves after they were found to be contaminated with horse meat.
Meanwhile, a major food factory has suspended all production.
The ABP Food Group, one of Europe's biggest suppliers and processors, stopped work at its Silvercrest Foods plant in Co Monaghan, Ireland, until further notice.
The firm said it believes the source of the contaminated material is one supplier after tests were carried out by Ireland's Agriculture ministry.