A man in his 40s has been arrested.
Revenue has seized more than 3.3 million cigarettes at Rosslare Europort in Co. Wexford.
Officers stopped a Polish registered truck which came on a ferry from France and found the cigarettes within its load.
They have a retail value of 2.4 million euro, which is a potential loss to the exchequer of over 1.8 million.
A man in his 40s is being questioned as part of the investigation.

Rising Fuel Costs Leads To Slow-Moving Protests Through Kildare
Missing Person Appeal: 17-Year-Old Joshua Treacy Is Missing From Maynooth
Man Due Before Criminal Court This Morning Following Drug Seizure
Gaelic Players Survey Reveals Drug Misuse Numbers
452 Incidents Reported In Naas General Hospital In Last Three Years
Over 600 Fewer Frontline Gardaí As Staffing Figures Release
Nationwide Fuel Protest Set To Take Place Tommorrow
Woman Dies In Crash As Over 3,000 Drivers Caught Speeding During Bank Holiday Weekend