Petrol prices are increasing despite huge falls in the cost of oil in recent months.
In the past few days prices at some petrol stations have increased by 2p a litre - or nearly 10p a gallon - adding £1 to the average fill-up.
It comes at a time when wholesale oil prices have dropped by nearly 40 per cent since July and the wholesale cost of the petrol and diesel is down 30 per cent.
Motoring groups accused the oil giants of profiteering at drivers' expense.
The AA called the price rises 'unbelievable, unjustifiable and totally outrageous'.
It revealed that the average price of petrol rose from 112.88p to 112.91p a litre - with some petrol stations charging much more.
Yet this week alone, the wholesale cost of petrol has dropped by about 10 per cent and the cost of oil has plummeted below $90 a barrel, from a high of $147 in July.
AA spokesman Luke Bosdet said: 'These dramatic falls should be filtering their way to the pumps by now.
'Instead, garages are putting on 1p and 2p a litre to screw a bit of extra cash before the inevitable drop.
'It looks as if garages are trying to squeeze a penny or 2p a litre extra out of motorists before prices do drop.
'It smacks of profiteering. It really is outrageous that pump prices should be rising when oil is plummeting.'
The AA has complained that average UK petrol prices had barely fallen despite oil prices 'crashing'.
Its monthly petrol price comparison shows prices fell by only one quarter of a penny over the past month, from 113.15p a litre in mid-August to 112.88p in mid-September.
However, these falls came before the latest price rises.
Enlarge petrol graphic
Wide variations between regional prices remained, with petrol in London - the most expensive area - costing nearly 2p a litre more than in Yorkshire-Humberside and the North-West.
One AA member emailed the organisation to warn: 'In my locality (South Buckinghamshire/Berkshire) the opposite has been happening with some garages charging up to 2p per litre MORE in the past few days.
'This has to be simple profiteering on the oil companies part. Is there nothing anyone can do?'
On Tuesday crude registered its biggest falls in four years to below $90 a barrel - less than a week after it crashed back through $100 a barrel.
The AA said there was scope to slash 4p a litre off petrol and 6p a litre off diesel.
The AA wants either a transparent track of wholesale prices matched against pump prices, or the creation of a government fuel price regulator to monitor the market.
Last month Shell unveiled record half-year profits of nearly £8billion following BP's half-year profits of £6.75billion.
But petrol retailers, supermarkets and oil companies deny profiteering.
Ray Holloway of the Petrol Retailers' Association, which represents 6,100 of the 9,200 filling stations, blamed currency fluctuations.
Mr Holloway said: 'Oil is traded in U.S. dollars and the British pound has fallen in value against the dollar, which is making the cost of fuel to UK customers more expensive.
'Without this currency difference, petrol and diesel would be up to 5p a litre cheaper in Britain.'
He said pump prices would fall by 4p a litre in October.
BP also blamed currency fluctuations, but said that despite this it had dropped its prices by about 8p a litre over the last month.
