Customs officers discovered an oil laundry facility and seized equipment following a surveillance operation in Co Monaghan today.
Officers from Revenue's Customs Service, assisted by gardaí from Carrickmacross and Castleblaney, made the discovery after a surveillance operation.
The facility - located one mile from the Border near Oram - had the capacity to store up to 200,000 litres of oil. An oil tanker was also seized in the operation.
The truck's driver, a man in his 20s from Northern Ireland, was arrested and charged with the illegal importation of hydrocarbon oil.
The laundry had the capacity to launder 50,000 litres of diesel per with the potential loss tot he Exchequer running to €780,000 per annum.
Cheaper agricultural diesel can be illegally "laundered" to remove a die and the end product sold on for a higher price as regular motor fuel.