Two diesel laundering plants, capable of producing nearly 120,000 litres of suspected illicit fuel and evading almost £12.5m in taxes a year, have been dismantled by HM Revenue and Customs (HMRC).

The finds follow the discovery of sites in Merseyside and Essex last month.

Officers from HMRC and Merseyside Police searched three premises on the Wirral and one in Liverpool, where they discovered a laundering plant in the Birkenhead area on Thursday 4 December.

More than 9,000 litres of suspected illicit fuel were removed from the site, along with equipment and chemicals. Three men from Merseyside were arrested in connection with the find.

A second laundering plant was discovered after HMRC searched premises in Ashford, Kent. Officers removed 12,000 litres of suspected illicit fuel from this site, dismantled the laundering plant and seized chemicals, equipment and separately a fuel tanker.

The operation involved over 100 HMRC officers, assisted by Merseyside, Lancashire, Essex, Kent, West Midlands and Staffordshire police forces. A further eight premises were searched during the activity and another five men were arrested in Essex, Lancashire and the West Midlands.

All those arrested have been bailed until April 2015 pending further enquiries. Investigations into the illegal fuel plants are continuing

Sandra Smith, assistant director, criminal investigation, HMRC, said: “It is wrong that honest businesses should be undercut by criminals involved in making or selling laundered fuel. Buying illicit fuel not only funds crime, it supports and encourages these dangerous activities within our communities.

“Every illegal laundering operation typically generates tonnes of toxic waste, involving significant safety and environmental issues. As taxpayers and local ratepayers, not only are we missing out on the stolen tax that ends up the pockets of the criminals, we are also paying the substantial clean-up and disposal costs. Anyone with information about fuel fraud should call the Customs Hotline on 0800 595000.”