Illegal fuel laundering should be "virtually eliminated" by next spring with the introduction of a new dye, Britain's Revenue and Customs has said.

It said it will be almost impossible to remove the marker put in tax-rebated fuel, which is intended for agricultural use.

It means a roadside check can easily detect motorists who use discounted red diesel.

Senior HMRC official Pat Curtis said: "The whole idea of this marker is to virtually eliminate laundering."

After a number of years of trials, the new fuel marker will be implemented in the Republic of Ireland and the UK in April 2015.

Red diesel is cheaper than regular diesel and is intended for off-road agricultural use.

Organised crime gangs have established sophisticated laundering plants to remove the dye, sourcing chemicals from China and using the internet to improve their techniques, Mr Curtis added.