Revenue officials have seized more than 20,000 litres of laundered diesel fuel in Dublin Port.
The fuel was contained in 1,000 litre containers concealed inside a refrigerated container unit on the back of a 13 meter lorry trailer.
The trailer, pumps and a fuel metering system - as well as a lorry - were also seized.
The fuel was being exported when it was intercepted by Customs officers as a result of ongoing surveillance activity focused on the illegal washing of agricultural or marked diesel.
Two men were questioned about the seizure by Customs officers, one in his 30s who is from Northern Ireland and a man in his 50s from Co Louth.
Files on both men are now being prepared for the Director of Public Prosecutions.