Figures from August show that the cost of fuel has risen the most in more than 20 years(Picture: Getty Images)

Drivers were hit by one of the biggest monthly fuel price rises in more than two decades in August, new figures have shown.

The RAC said the 7p per litre spike in the average cost of petrol in August was the fifth largest monthly increase in 23 years.

The 8p per litre hike in diesel prices was the sixth largest over the same period.

The RAC said rising pump prices are being caused by an increase in the cost of oil, which has gone up by nearly 12 US dollars a barrel since the start of July to nearly 87 US dollars due to producing group Opec+ reducing supply.

This led to the wholesale cost of fuel – what retailers pay – going up, which has been passed on to drivers at forecourts.

Fuel prices have gone down from the highs seen after the Russian invasion of Ukraine last year (Picture: AFP)

Earlier this week data from the Confused.com fuel index, which organises the country by postcode, the best areas for cheaper petrol include Lancashire, South Wales and Northern Ireland.

In fact, the Belfast postcode – which covers all of Northern Ireland – currently has the cheapest petrol in the country, with an average price of 145.1p per litre.

The fuel across the Irish Sea is considerably cheaper than the average for any area on the island of Great Britain, as the Torquay postcode takes second place with a jump up to 146.7p per litre.

Rounding out the top five lowest petrol prices in the UK are the Sunderland (146.8p), Bradford (147.0p) and Kilmarnock (147.2p) postcodes.

Meanwhile, the most expensive areas in the country for petrol are dominated by Scottish islands and parts of London.

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RAC fuel spokesman Simon Williams said: ‘August was a big shock to drivers as they had grown used to seeing far lower prices than last summer’s record highs.

‘Seeing £4 or more go on to the cost of a tank in the space of just a few weeks from a pump price rise of 6-7p a litre is galling, particularly for those who drive lots of miles or run an older, less fuel-efficient car.

‘While the increase is clearly bad news for drivers, it could have been far worse had the biggest retailers not let their inflated margins from earlier in the year return to more normal levels as wholesale fuel costs went up.’

‘All we can hope is that this move by many big retailers back to fairer forecourt pricing remains when wholesale costs go down again. Only time will tell.’

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