Customs officers have seized 600,000 cigarettes in Dublin port.
The Marlboro-branded tobacco had a retail value of 304,000 euro and was discovered when officers examined a large wooden crate which had arrived from the Far East.
The cigarettes were concealed beneath a layer of shoes.
A Customs Services spokesman said: "Investigations are ongoing with a view to referring a file for criminal prosecution."
The cigarettes and tobacco represented a potential loss to the Exchequer of approximately 261,000 euro, the organisation added.