Motorists' pockets being plundered by retailers, says AA
The AA has accused fuel retailers of "plundering drivers' pockets" by putting up the price of petrol and diesel disproportionately.
Over the last month it said that the price of oil has fallen by nearly 5% - whereas petrol prices are up by 1.2%.
It said motorists are now paying an extra 1.73p a litre of petrol, and an extra 0.63p a litre of diesel.
However, the industry said it was wholesale costs that had risen, making increases at the pump inevitable.
One reason was that oil is priced in dollars, and the pound has fallen significantly against the dollar.
Since the middle of March, the exchange rate is down from $1.51 to the pound, to $1.48.
The wholesale cost of petrol - which includes the cost of refining and transport - rose from $608 a tonne at the beginning of March, to $613 in the first fortnight of April.
But Edmund King, the AA's president, said motorists were still losing out.
"Cars are like blank cheques for whoever feels the need to balance the books by plundering drivers' pockets," he said.
Last month the RAC accused retailers of putting up the price of diesel, even though the wholesale cost had fallen.
At the time, retailers said the margins they made were "tiny", and that many petrol stations were closing as a result.
"Now the fuel retailers are taking £3 a tank extra on diesel to steady their finances," said Edmund King.