Drivers were hit by one of the biggest monthly fuel price rises in over 20 years in August as petrol shot up by nearly 7p a litre and diesel by 8p.

August saw drivers hit by one of the biggest monthly fuel price rises in 23 years

It meant the average price of unleaded finished the month at 152.25p – up from 145.57p and adding nearly £4 to a tank (£80 to £83.74), RAC data reveals. Diesel went up from 146.36p to 154.37p, making a fill-up nearly £4.50 (£4.41) more expensive.

The rising prices at the pumps have been caused by increases in the cost of oil, due to producer group OPEC+ reducing supply.

But rises could have been higher, had big retailers not let their margins go back to more normal levels – which the RAC said showed retailers had been influenced by the Competitions and Markets Authority report earlier this summer, which revealed supermarket margins on fuel increased 6ppl from 2019 to 2022.

RAC fuel spokesman Simon Williams explained: “All of a sudden, margins are once again closer to their longer-term averages. It appears they used the wholesale price rise to subtly cover their tracks – after all, big reductions at the pumps soon after the CMA’s findings were announced would perhaps have been far too obvious a step.”

Whether prices continue to go up in the coming weeks remains to be seen – but concerns about the health of the Chinese economy and the end of the summer driving season in the United States could limit further rises.

Despite the fall in retailer margins, fuel prices in Northern Ireland are still lower, with petrol at an average of 149.5p and diesel at 151.6p, the RAC pointed out. But the gap has shrunk by around 2p a litre in a month and petrol is now only 1.5p cheaper in Northern Ireland while diesel is 2p less.

The Government is still pushing ahead with plans to make fuel retailers display live fuel prices – former Energy Secretary Grant Shapps warned retailers last month that he would “call out any foot-dragging” over the sharing of pump price data.

Drivers can also use the Fuel Finder feature in the free myRAC app from the App Store or Google Play to help find the cheapest fuel sites within a given area, compared to UK average prices for both petrol and diesel.