Revenue officers seized 2.3 million smuggled cigarettes at Dublin Port on Monday.
The seized cigarettes, which originated in Belarus, have a retail value of over €1.2m, and represent a potential loss to the Exchequer of over €1m.
They had arrived at the port in a container from Rotterdam and were found as a result of routine profiling by officers.
Revenue says that investigations are ongoing.
Yesterday, 12,000 unstamped cigarettes were seized by Revenue officers during the search of a house in North County Dublin.
The cigarettes, branded Marlboro Gold, originated in the Ukraine and have an estimated retail value of over €6,400.