Four men have been arrested after nine million contraband cigarettes were recovered when a truck and a 4x4 were stopped and searched.
Gardai pulled the vehicles in at a service station on the M1 motorway near Castlebellingham, Co Louth, and recovered the black market haul.
The cigarettes had a street value of about 4.3 million euro and, if sold, would have run up a 3.7 million-euro loss to the state.
The arrested men, in their late 30s and early 40s, were taken in for questioning to Drogheda and Dundalk Garda stations.
A number of follow-up searches were carried out in businesses and homes.