The Food Safety Authority (FSA) has opened an investigation following the discovery of meat with illegal health labels at a processing plant in Co Monaghan.
The FSA said it had uncovered sheets of self adhesive labels with "illicit health marks" at M&N Meats Ltd in Ballybay.
The health mark is an official stamp on the surface of meat or on the label of packaged meat providing information about the country of origin and the official number of the slaughterhouse or cutting plant.
The FSA said its investigations followed information from the Food Standards Agency Northern Ireland relating to an investigation of Euro Freeze (Ireland) Ltd processor at Lisnaskea in Co Fermanagh.
The North's agency seized records from Euro Freeze that revealed it had sent a number of consignments to premises in the Republic.
The FSA inspected these premises to validate the authenticity of the health marks. It said the focus of its investigation is on repackaging, relabelling and distribution of meat and poultry.
FSA inspectors have also searched the premises of D'Arcy Foods, Ballybay, Co Monaghan, and records have been removed from the premises for further examination.
The FSA said: "Any product found with illicit health marks will be detained and will be removed from the market."
It said: "To date, one consignment of beef with suspect health marks has been detained and is being inspected."