Customs officers have seized a consignment of 2.3 million illegally imported cigarettes following a surveillance operation at Drogheda Port.
The cigarettes were found hidden in a container on board a ship that had arrived from Rotterdam.
The discovery was made last weekend, but was only announced today.
Customs officers said the haul could have cost the Exchequer €550,000 in lost tax revenue, although it is believed to have been destined for the North or Britain.