Tractor parades at events such as Cardigan's Barley Saturday will not be permitted to run on rebated red diesel from April, HMRC has warned.

The new rules have implications for those taking part in charity tractor runs and vintage shows, which are popular across rural west Wales.

Red diesel, which is dyed so it is easily identifiable, is taxed at a much lower rate for machinery used in agriculture, horticulture, fish farming and forestry.

The UK government says the rule changes, whilst not severely impacting farming processes, "will help meet its climate change and air quality targets."

A spokesperson for HMRC confirmed: "Agricultural vehicles used for tractor runs would not be considered an accepted agricultural use.

"Users will either need to consider using some vehicles for non-accepted use and others for accepted use, or use fully duty paid diesel for all uses."

Mark Jukes, chairman of Barley Saturday in Cardigan, said the rules will have implications for those parading tractors at this year's event.

"There's the inconvenience for somebody who uses the tractor for agriculture, but when it comes to showing, they have to change the diesel, and basically, the cost is twice as much," he told the BBC.

"There's a lot of people interested in seeing these tractors, tractor runs also raise money for charities which is quite an important part of the local community, and I think there will be few upset people.

"We'll be giving guidance to say that if you're coming you have to have white diesel in the tractors."

A spokesperson for the HMRC said it would remove the entitlement to use red diesel and rebated biodiesel from most sectors from April 2022.

He added: "The tax changes will ensure that most users of red diesel use fuel taxed at the standard rate for diesel from April 2022, like motorists.

"This more fairly reflects the harmful impact of the emissions they produce.

"Removing most red diesel entitlements will also help to ensure that the tax system incentivises users of polluting fuels like diesel to improve the energy efficiency of their vehicles and machinery, invest in cleaner alternatives, or just use less fuel."