Customs officers have uncovered an oil laundering plant near the Border after a surveillance operation.
Backed up by gardai, officers found the plant in a disused mushroom house in Clontibret, Co Monaghan.
It was the seventh laundering plant raided so far this year.
It had the capacity to launder about two million litres of fuel a year with a potential loss to the Exchequer of €1m annually.
Officers seized 10,000 litres of fuel, nine bags of bleaching agent, a car and a van.