The average cost of filling a typical family car is expected to exceed £100 in the largest daily price jump in 17 years.
A litre of petrol cost an average of 180.7p on Tuesday, according to data firm Experian Catalist, a rise of 2.2p compared with the previous day.
A similar increase is set to take the average cost of a full tank for a 55-litre family car to more than £100 for the first time.
The average cost for the day will be published on Thursday morning.
It comes amid the government’s continued concern that the 5p cut implemented by Chancellor Rishi Sunak in March is still not being reflected in pump prices at all filling stations.
Downing Street indicated that fuel retailers failing to pass on the fuel duty cut could be named and shamed.
The prime minister’s official spokesman said: “We are continuing to look at all possible options. Transparency may have an important role to play.
“It is important the public understand what actions each of the fuel retailers are taking and so we are considering what further options we can take in this area.”
Some forecourts across the country are already selling petrol above £2 per litre, price comparison website PetrolPrices reported.
Highest petrol prices at BP sites
The highest price so far has been recorded as 202.9p at BP sites on the A1 near Sunderland, Tyne and Wear; the M4 near Chippenham, Wiltshire; and the M6 near Burton-in-Kendal, Cumbria.
Meanwhile, the most expensive forecourts on local roads are selling fuel at up to 196.9p per litre in Glasgow and near Stafford, Staffordshire.
Average diesel prices are also at a record high, hitting 186.6p on Tuesday, up 1.4p from Monday.
RAC fuel spokesperson Simon Williams said: “The average price of petrol endured its biggest daily jump in 17 years by going more than 2p (2.23p) a litre on Tuesday taking it to nearly 181p a litre (180.73p).
“Diesel increased by almost 1.5p to yet another record high at 186.57p. A full tank of unleaded has now shot up to £99.40, moving us ever closer to the milestone £100 petrol fill-up – an unfortunate landmark we may reach as soon as tomorrow.”
Asda hikes petrol prices
“Asda hiked its average petrol price nearly 5p a litre in a single day, which is unheard of.
“These are unprecedented times in terms of the accelerating cost of forecourt fuel.”
He warned that “we are still some way from the peak” as it will take several days for an unexpected fall in wholesale costs on Tuesday to be reflected in pump prices.
An Asda spokesman told Sky News: “The wholesale price of fuel has increased at an unprecedented rate, rising by over 9p per litre in the last week.
“Motorists trust us to provide the best value at the pumps and we will do all we can to minimise the impact of rising wholesale prices on our customers.”
AA spokesman Luke Bosdet described Tuesday’s more than 2p-a-litre leap in average UK petrol prices as a “huge shock”.
“The government needs to act fast to rein in these excesses,” he added.
“The example of fuel price transparency in Northern Ireland, where petrol and diesel two days ago averaged 6p a litre cheaper than the UK average, shows a way forward that will revive competition and can be implemented in a matter of weeks.”
The Consumer Council of Northern Ireland monitors the country’s fuel prices.