Customs officers today seized around 3.3 million cigarettes with a retail value in the order of €1 million, it has emerged.
The cigarettes were smuggled into Ireland concealed in the bases of two flat-rack containers at Dublin Port having come from Saudi Arabia.
The containers arrived by ship on May 25 thand were kept under surveillance in an operation code named "Jacob".
Officers moved in last Saturday when the containers were moved to a rural part of Co Tipperary.
Three people were detained and later released and investigations are continuing both nationally and internationally.
"Smuggling of cigarettes in flat-rack containers is now recognised internationally as a particularly effective method used by sophisticated groups to smuggle contraband.
"Flat-rack containers do not normally attract the attention of law enforcement, as they appear at face value to be empty.
"The potential loss of revenue, had the cigarettes been successfully diverted on the domestic market, has been calculated as €880,000," a Customs spokesman said.