A man was arrested after a fuel laundering plant was discovered in Co Down yesterday.
The plant was capable of producing around 250,000 litres of illicit fuel a year.
It was hidden in farm buildings in the Banbridge area.
HM Revenue and Customs seized a fuel pump, 750 litres of fuel and 1,000 litres of waste.
In follow-up searches, a further 600 litres of fuel, a fuel storage tank, pumping equipment and a taxi were also seized.
The 51-year-old was released on bail after questioning.
Investigations are continuing.