Motorists have been warned that petrol prices may soon reach their highest level ever.
The AA said sterling's slide against the dollar and market speculation could push prices to record levels by Easter.
The warning comes as tanker drivers at the Grangemouth refinery, which supplies Scotland, Northern Ireland and northern England, started a three-day strike in a row over pay and pensions.
The strike, involving 42 Unite members at the refinery near Falkirk, will run until Monday morning with striking workers taking turns to man the picket lines.
After surging 5p a litre over the past month, the price of petrol at the pumps has gone up a further 1p in the last five days, the AA said.
It revealed that the average cost of petrol in the UK is now 138.32p per litre, with diesel having risen 4.78p from its mid-January price to stand at an average of 145.10p.
The latest figures show that petrol has risen 6.24p since early January, adding £3.12 to the cost of filling a typical 50-litre tank.
The AA said the cost of filling up the 70-litre tank of a Ford Mondeo now costs £4.37 more than it did six weeks ago.
A two-car family's monthly petrol cost has risen £13.25.
Drivers have been caught between the pound weakening against the dollar and soaring wholesale prices, both due to stock market speculation.
Regionally, Yorkshire and Humberside and the north of England are the cheapest for petrol at the moment at 137.6p a litre, with prices in London and Scotland at 137.8p. Northern Ireland is the most expensive at 138.7p.
Yorkshire and Humberside remains the cheapest region for diesel, averaging 144.2p, while East Anglia, Northern Ireland and southeast England are the most expensive at 145.2p.
AA president Edmund King said: "We're no longer talking of the motorist as a cash cow for tax and speculator greed, but a horse slowly but surely being flogged to death.
"This is the third 10p-a-litre wholesale price surge in 11 months, given extra vigour by currency speculators betting against the pound."
Government revenue from fuel duty has also been hit hard as Britons reduce spending by cutting back on non-essential journeys.
HM Revenue and Customs figures showed that January's UK petrol sales fell to the lowest tracked by the Government in 23 years.
Drivers consumed 1.465 billion litres of petrol last month, down 14 million litres on the previous all-time low set in March last year and nearly 100 million litres below December's consumption of 1.564billion litres.
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