A HMRC operation targeting oil related fraud worth £10m has led to the arrest of 11 people across the UK.
The Revenue said more than 100 of its officials supported by police officers executed search warrants at business and domestic addresses in North London, Cheshire, Essex and Londonderry and Armagh in Northern Ireland.
Criminals involved in the fraud purchased duty rebated gas oil and kerosene from legitimate suppliers by manipulating the Registered Dealers in Controlled Oils Scheme and laundered and/or mixed the rebated oil for illegal use in road vehicles.
Peter Hollier, HMRC criminal investigations, said: "Organised criminals are attacking the tax system in many different ways with the aim of stealing huge amounts of revenue.
"[The] operation, yet another large undertaking by HMRC, is part of a large-scale criminal investigation into oils related frauds that may run to millions of pounds over several years. We are committed to tackling this type of fraud and to showing the criminals behind it, wherever they operate in the UK, that there are no safe havens."