Motoring organisations across Europe have demanded the European Union launch an investigation into soaring petrol prices.
The Federation Nationale de l'Automobile (FIA), which represents 35 million drivers and counts both the AA and RAC as members, has written to the EU claiming the way prices are determined is "far from transparent".
UK petrol prices hit record levels last month as the wholesale price of oil soared, but have been much slower to come down as the price of crude oil dropped back again. A full tank for an average European car now costs over £10 more than it did a year ago.
The FIA letter calls for an inquiry into how benchmark prices are set on the Rotterdam spot market, where cargoes of petrol and diesel for the whole European market are bought and sold.
Werner Krauss, chairman of the FIA Eurocouncil said in the letter that "a platform with such a small volume is doubted to be a representative indicator for the vast European market".
Mr Krauss also wants the EU to look into the role of speculation on oil prices, adding that the FIA is very concerned about the "resulting volatility in fuel prices and negative financial impact on consumers".
Luke Bosdet, of the AA, said "No one is giving us any answers as to why petrol prices are so high. We need greater transparency so that everyone can see we are paying a fair price for fuel".
The AA wants to see an independent regulator to balance the interests of the supplier, retailer and customer.
The British Petrol Retailer's Association, which represents 6,000 petrol station owners, also expressed concern about the issue of transparency. It is to press the UK Office of Fair Trading to look into whether its members are getting a fair deal.