Both the European Commission and the OFT are coming under mounting pressure to investigate and regulate the way petrol prices are set as motorists struggle to meet the soaring costs of fuel in the UK.

An alliance of European motoring organisations the Federation Internationale de l'Automobile announced this week that it had written to the European Commission calling for an examination of EU fuel prices. The group, which represents 35 million drivers and includes the RAC and AA in the UK, said the way petrol prices were currently set needed to be made clearer.

"Basically we have seen wholesale Northern European oil and petrol prices reach the record levels they did in 2008, yet raw material costs now are 10% to 20% less," said AA spokesman Luke Bosdet.

"We want to find out why. We want more transparency so it is possible to see whether the retailers are passing on price increases fairly or not."

In the UK, the AA was also calling on the government to introduce a regulator to act as an "honest broker to ensure everyone is acting fairly", said Bosdet.

Average UK pump prices have already reached record levels. This Easter, petrol was 14.92ppl more expensive than last year and diesel was 20.09p pricier.

In spite of this, independent forecourt retailers complained this week that supermarket fuel prices were now too low and were pricing them out of the market. The British Petrol Retailers Association called on the OFT to examine fuel prices in the UK.

"Many independent petrol retailers are caught up in a five-year fixed agreement and therefore cannot lower their prices to compete," said chairman Brian Madderson.

Supermarkets were merely offering the best deal they could for consumers, said Richard Dodd of the British Retail Consortium.

"I don't think that anyone should be criticising retailers looking to offer competitive prices for ­consumers," he said.