The UK government is investigating a fast-growing “green fuel” called HVO diesel amid claims of significant fraud, the BBC has learned.

HVO is increasingly popular as a transport fuel and for powering music festivals and its backers say it can curb carbon emissions by up to 90% as it can be made from waste materials like used cooking oil.

But industry whistleblowers told the BBC they believe large amounts of these materials are not waste but instead are virgin palm oil, which is being fraudulently relabelled.

And data analysed by the BBC and shared with the UK’s Department for Transport casts further doubt on one of the key ingredients in HVO, a material called palm sludge waste.