Custom officers have seized almost one million contraband cigarettes with a retail value of around €511,000 in non-related operations in Cork and Dublin.
It represents a potential loss to the Exchequer of €411,000.
900,000 "Mayfair" branded cigarettes were discovered at Dublin Port earlier in a shipment from the Netherlands of five pallets described as "catering equipment".
Investigations are ongoing.
In two separate operations in the past week, Revenue officers seized 29,000 cigarettes in Cork and at Dublin Airport.