Revenue officers seized 8.3 million contraband cigarettes that arrived into Ireland on Tuesday and Wednesday of this week.
The cigarettes came into Dublin from China via Rotterdam.
In an intelligence-led operation, Revenue's mobile x-ray scanner and detector dog 'Grace' discovered the cigarettes in a shipping container.
They were branded 'Richmond', 'Eton' and 'Gold Classic'.
The consignment, which was said to contain 'clothing', was followed to Limerick.
Revenue officers carried out searches under warrant of premises there, and these investigations are ongoing with a view to prosecution.
The seized cigarettes have a retail value of more than €4m, representing a potential loss to the exchequer of €2.9m.