May was a “hellish month for motorists” as prices jumped by 6p – the highest monthly fuel rise in 18 years, the RAC says.

Pump prices have risen every day since April 22 with the cost of unleaded shooting from 123.43p to 129.41p throughout May.

A driver filling up a 55-litre tank for their family car would pay £3.29 more at the end of last month compared to the start of May, the RAC says.

Diesel saw a greater monthly increase, with the average price jumping by 6.12p a litre in a month, from 126.27p to 132.39p, the second highest diesel rise this century .

The cost of a tank of diesel for a family car became £3.37 more expensive during May at £72.81.

In the Huddersfield area Sainsbury’s at Shorehead sold unleaded today (Tues) at 124.9p and diesel 126.9 while Morrisons at Waterloo it was 124.7p for unleaded and 129.7 for diesel.

Asda at Bradley sold unleaded for 124.7 and 128.7 for diesel while Jet, the independent fuel retailer at Scar Lane, Milnsbridge , sold it for 128.9 for unleaded and 130.9 for diesel.

RAC fuel spokesman Simon Williams said: “May was a hellish month for motorists.

“Sadly, they have been besieged by pump price rises for three months with nearly 9p a litre being added to petrol since the beginning of March.

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“The rising oil price together with a weaker pound is a punitive combination for anyone that drives regularly.

“For many people there is little alternative to the car for the majority of journeys they have to make, so it is therefore very difficult to avoid feeling the pinch of rising pump prices.”

Rising oil prices - due to political tensions between the USA and some oil exporting nations - are one reason for the increased cost. The price of oil passed the 80 USD a barrel mark (£60) twice during May.

FairFuelUK, a group which campaigns for lower fuel duty and “transparent” pump prices, is accusing oil companies of taking advantage of political tensions to keep pump prices artificially high.

Founder Howard Cox says businesses involved in petrol are “exploiting” motorists by not reducing pump prices when oil costs do fall.

He said: “Current pump prices are 1p-2p per litre more than they need be, despite escalating oil costs and the weaker pound. Greedy opportunistic oil speculators along with OPEC and Russia’s oil production levels posturing, are using geo-political spats between the USA and Iran to deliberately over inflate the cost of filling up.”

Fuel comparison website Petrol Prices report the cheapest fuel currently at Asda, with an average charge for unleaded petrol of 124.8p and diesel 128p and the highest at BP with unleaded at 131.3p and diesel at 134.4p.