Diesel drivers are paying around 20p more for every litre of fuel compared to motorists with petrol cars - with the gap in no way reflecting wholesale prices - claims the RAC.

With just a 6p difference between the two wholesale prices throughout February, motoring experts say diesel drivers are being unnecessarily 'overcharged', as fears grow the Chancellor could also be about to also axe the 5p duty cut brought in last year.

RAC's Fuelwatch research has found the nation's 12 million diesel car owners are, on average, paying an extra £11 more for a full tank of fuel, with the risk that this could increase further if the 5p cut introduced a year ago isn't maintained by the Chancellor in two week's time.

The RAC is worried drivers could be in for 'pump price shock' in little under a fortnight.

While the disparity between diesel and petrol prices is larger than it needs to be, insists the RAC, February saw the average price of a litre of unleaded come down another penny to 147.72p, while diesel dropped 3.19p to 167.19p.

But if the duty cut is removed in the spring budget on March 15, current petrol prices could rise to 153.72p and diesel to 173.19p when factoring in VAT.

RAC fuel spokesman Simon Williams said while a reduction in prices at the pumps this month is welcome news for drivers facing increases in the price of so many other everyday items, motorists with diesel cars appear to be getting a raw deal.

He explained: "Retailers really ought to demonstrate they’re on the side of drivers by cutting their diesel prices now – not least as the wholesale price is on a par with where it was 12 months ago, yet the price they’re charging drivers at the pumps remains needlessly high.

"All eyes are now on what the Chancellor decides to do with fuel duty at the Budget in just two weeks’ time. While we accept the 5p cut introduced last year can’t last forever, with household finances under even more pressure this spring than they were a year ago, we don’t think now is the time to be removing it.

Any change, says Simon, to the VAT cut could mean the UK would have the most expensive diesel in Europe.

He added: "To decide to raise prices by 5p on both fuels would prove punishing to households and businesses struggling to make ends meet, and may have a detrimental effect on both inflation – which the government is desperate to bring down – and the wider economy.

"In the case of diesel, it would also mean the UK has the highest fuel duty rate in the whole of Europe."