Customs officials have seized three million cigarettes, bringing this year's total figure to more than 130 million.
The total cigarette haul so far has a retail value of more than €55m, with a potential loss to the State of more than €43m in excise and VAT.
The latest find was hidden in a tyre consignment on the M1 near Drogheda, Co Louth.
One person is being questioned.
The cigarettes were hidden inside a consignment of tyres which had arrived in Cork Port earlier this week from the United Arab Emirates.
It is believed they were destined for sale in Northern Ireland and the Republic.
On Wednesday, Revenue seized four million cigarettes in Co Laois. The cigarettes were in a container that had earlier arrived in Dublin Port.
These had a potential retail value of €1.7m and a potential loss to the exchequer of €1.3m.
Four individuals have been questioned in relation to the find and a file is being prepared for the Director of Public Prosecutions.
The number of seizures so far this year is 5,221, involving a quantity of 131 million cigarettes, the Revenue figures show. Included in this figure are 83,316,294 'counterfeit' cigarettes.
The total seized had an estimated retail value of €54,213,166.
Major seizures this year have included eight million cigarettes in a warehouse in Ashbourne, Co Meath in July.
The cigarettes had arrived in Dublin Port in a container earlier from Malaysia via Rotterdam.
Shortly afterwards customs officers, backed up by gardai, entered the premises and seized the cigarettes.
Other major seizures include the 10.5m cigarettes seized in Dublin Port last May, while around 28m were seized in Dundalk in February.
Revenue also told the Herald that there have been 672 seizures of "roll your own" and pipe tobacco so far in 2010.
The amount, 2,162kg, had an estimated retail value of €776,639 and potential excise and VAT duties of €611,759.
In one weekend in July, Customs seized almost 500,000 cigarettes in an operation targeting gangs from Lithuania.