May saw average diesel prices climb to new heights with a litre hitting 183p, a hike of more than 5p in the month, according to new data from the RAC.

The increase means the cost of filling up a diesel car went above the £100 mark for the first time ever.

Meanwhile, the average price of petrol increased by 11p per litre (ppl) in May – the second largest monthly increase ever seen.

A litre of unleaded rose from 162.87p at the start of May to 174.02p by the close. This was less than a penny short of the all-time biggest rise recorded in March when a litre of petrol jumped by 11.61p (151.67p to 163.28p).

The major difference with the May rise, however, is that this happened after the historic 5p-a-litre duty cut announced by Chancellor Rishi Sunak on March 23. Despite this, the cost of a litre has rocketed to yet another record high.

The pump price hike has been driven by oil rising from $106.07 to a late month high of $124.45 (31 May) – a 17% increase, combined with a weaker pound at $1.2 – an important factor as fuel, like oil, is traded in dollars on the wholesale market which can dramatically affect the price retailers pay to buy it.

RAC fuel spokesman Simon Williams said: “Since Russia invaded Ukraine on 24 February the price petrol has gone up 24p a litre, for diesel the figure is 30p.

“This means the cost of filling a 55-litre petrol car has gone up by £13, and a diesel one by £16.50. Both of these figures would have been even higher had the Government not cut fuel duty.

“While it’s hard to imagine prices getting much worse, the wholesale price of petrol has now gone above diesel which spells yet more bad news at the pumps in the coming weeks.”

The average price of a litre of unleaded across the big four supermarkets, which dominate UK fuel retailing, went up nearly 9p from 160.31p at the beginning of May to 169.05p by the end. Diesel increased from 174.18p to 180.38p – a jump of 6p a litre.

On the motorway a litre of petrol closed May at 187.66p, up by nearly 5.5p from 182.19p at the start. Diesel finished the month at 197.71p, up from 192.5p, with the prospect of hitting £2 a litre very real in the near future.

In terms of where prices might head next, the RAC expects average petrol prices to hit 185p as a result of the rising cost of oil, with diesel heading towards the 190p mark.

As of today (Monday, June 6), the relentless run of record fuel prices continued over the bank holiday with the average price of petrol having now increased by almost 4p a litre since the end of May. A litre of unleaded is now 177.88p, while diesel is 185p, an increase of 2p already this month. This means a tank of petrol now costs nearly £98 (£97.83) and diesel nearly £102 (£101.81).

Williams said: “With oil above $120 a barrel and sterling still at $1.2, worse is still to come. Sadly, we expect to see the average price of petrol break through the 180p mark this week with diesel moving further towards 190p.

“More radical Government intervention is urgently needed, whether that’s in the form of a further reduction in fuel duty or a VAT cut. As it is, drivers surely won’t be able to cope unless something is done to help. This is fast becoming a national crisis for the country’s 32m car drivers as well as countless businesses.”

> Regional petrol and diesel prices, with data supplied by Allstar