Customs officials in Northern Ireland have uncovered the UK's largest fuel laundering operation.
The diesel laundering plant found close to the Irish border near Crossmaglen, Co Armagh, was capable of producing over 30 million litres of illicit fuel a year, costing the taxpayer an estimated £20 million in lost revenue.
Police and HM Revenue and Customs (HMRC) officers uncovered the plant on Tuesday morning when they searched agricultural buildings. A man arrested in connection with the find has been released on bail pending further inquiries.
The investigators seized six large fuel storage tanks, 37,000 litres of illicit fuel, 1,000 litres of acid, pumps and associated equipment. They also removed almost 21,000 litres of toxic waste found stored in barrels and in an underground slurry pit.
HMRC assistant director of criminal investigation John Whiting said: "This is fuel fraud on an industrial scale. The sheer size of this illegal operation is staggering and far exceeds anything we have ever come across before.
"This activity would have generated massive revenue loss as well as tonnes of toxic waste - its economic and environmental impact on Northern Ireland would have been considerable."
He added: "The location of this illegal operation would suggest that the fuel was destined for both sides of the border, resulting in losses to both the UK and Republic of Ireland exchequers.
"This operation shows the success of multi-agency co-operation in tackling fuel fraud and why we will continue to work with our partners, as part of the Organised Crime Task Force, in the fight against organised crime."
Laundered fuel is red, or green, diesel which has been filtered through chemicals or acids to remove the government marker.
The chemicals and acids remain in the fuel and damage fuel pumps in diesel cars.