Gardaí and Revenue officers have uncovered a fuel laundering plant in a commercial premises in Portlaw, Co Waterford.
The plant had the capacity to launder a total of 10m litres per annum, with a potential loss to the Exchequer of approximately €5m.
The operation, which was discovered over the weekend, is being dismantled tonight.
Gardaí are investigating if the fuel laundering operation has connections with other parts of the country.
No arrests have been made.