A gang with links to the "Real IRA" is suspected of running a large diesel laundering operation that was raided by customs officers from Dundalk early yesterday morning.
It was hidden in a large shed that straddles the Border and has been confirmed as the largest such plant seized in the State to date.
It also contained an electronic switching system that controlled the chemical process used to remove dye from agricultural diesel. This process allows the processed diesel to be sold as clean or white diesel to unsuspecting motorists.
The switching system was elaborate and included hydrometers and it is the first time customs officers are aware of it being used in either the State or the UK.
The scale of the washing or so-called laundering operation, which could have processed 150,000 litres of oil a day, also means it would have represented a massive loss of duties to the State if it had not been discovered. This could have totalled millions of euros a year; however, the plant is believed to have been operating for just a number of weeks.
Customs officers from Dundalk, led by senior officer Sean Brosnan, raided the large shed concealing the operation in the early hours of yesterday morning.
The machinery was up and running and they recovered approximately 100,000 litres of diesel in various stages of being washed.
The shed it was hidden in was at Raskeagh, Kilcurry, about five miles from Dundalk and while the entrance to it is in the State, the rear wall of the shed is in Tiffcrumm, Co Armagh.
Inside the shed, officers found five large tanks. There was a large tank full of red-coloured diesel, which is sold in the North, and another full of green diesel, sold for agricultural purposes in the State. The tanks were attached by hoses to the cleaning system, including the chemicals and acids used to remove the dye. The washed product was pumped into larger tanks, similar in size to bulk tankers.
The finished product is traditionally smuggled in concealed tankers to a network of operators who then sell it to motorists, the unwitting target market for this criminal operation.
Garda sources are confident that a gang, possibly made up of six men, all from the north Louth area and with strong links to the "Real IRA", were running the operation.
The gang is believed to have been giving a percentage of the profits from the operation to the "Real IRA".
The investigation into the whole operation was continuing last night.
Customs officers say they know who the culprits are and they will be preparing files for the Director of Public Prosecutions on them.