Supermarkets have more than doubled their margins on fuel since the start of the war in Ukraine, new analysis suggests.

The RAC said Asda, Tesco, Morrisons and Sainsbury’s were making an average of around 4.7p per litre on fuel sales when the Russian invasion began in February 2022.

The motoring services company found this had increased to around 10p per litre, leading to higher pump prices.

Everyone is paying more than they should be to a lesser or greater extent depending on where they live

Supermarket fuel margins were 2.3p per litre in 2016.

Lower fuel prices helped drive a drop in the Consumer Prices Index measure of inflation last month to 7.9%, down from 8.7% in May.

RAC fuel spokesman Simon Williams said the decline could have been even sharper if supermarket pump price reductions were “in line with cheaper wholesale costs”.

He went on: “While we accept the cost of running forecourts might have increased, these bloated margins must make difficult reading for the millions of drivers who are already battling the rising cost of living.

(The CMA's) recommendation that a price monitoring body is set up and that retailers are mandated to provide live prices for fuel finder apps is very welcome and long overdue

“In short, this means everyone is paying more than they should be to a lesser or greater extent depending on where they live.

“We hope artificially high pump prices will become a thing of the past due to the actions promised by the Government resulting from the Competition and Markets Authority (CMA) report earlier this month that showed supermarkets had overcharged drivers to the tune of £900 million last year.

“Their recommendation that a price monitoring body is set up and that retailers are mandated to provide live prices for fuel finder apps is very welcome and long overdue.”

CMA director of markets Dan Turnbull told the Commons’ Business and Trade Committee on Wednesday that Asda’s pence per litre fuel margin targets were three times higher this year than in 2019.

He added that the retailer deliberately passed on reductions in wholesale costs more slowly in areas where it had no competition.

An Asda spokesperson said: “Asda is proud to be a fuel price leader – and an Asda petrol station in a local area keeps prices down for all motorists. In support of calls for greater transparency in fuel pricing, we will be making our prices visible for all of our fuel stations in the coming weeks so motorists can be confident they are getting the best prices when filling up at Asda.”

Supermarket fuel retailers were approached for a comment.