A planned 5p rise in fuel duty could cause “untold damage” if the Government decides to go ahead with it in the next budget, warns RAC Fuel Watch.

It says drivers face a “pump price shock” in less than two weeks unless the Chancellor decides to keep the 5p duty cut put in place a year ago, and cancel the annual planned hike at the Spring Budget on 15 March.

RAC fuel spokesman Simon Williams said: “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.

“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.

“We also hope Mr Hunt isn’t about to become the first Chancellor in 12 years not to cancel the annual planned fuel duty rise. If he were to go ahead with it, untold damage could be caused.”

February saw the average price of a litre of unleaded come down another penny (1.26p) to 147.72p, while diesel dropped 3.19p to 167.19p. The falls make the cost of filling a 55-litre family petrol car £81.25 (down £0.69 from £81.94 a month earlier), and the diesel equivalent £91.95 (down from £93.71 at the start of February).

While the reduction in diesel prices is good news, wholesale price data analysed by the RAC shows drivers of the UK’s 12m diesel cars continue to pay a “needlessly high” price every time they fill up. Despite there being just a 6p difference between the wholesale prices of both diesel and petrol throughout all of February, diesel pump prices are currently 20p more than petrol. This means anyone filling a diesel car is, the RAC calculates, paying around £7 more per tank than they should be if diesel was being sold at a fairer price of around 155p a litre.

Last month, the RAC revealed that drivers of diesel vehicles are paying 20p per litre more for diesel than petrol, despite a wholesale cost difference of just 6p.