The European Union has launched an antitrust investigation into possible price manipulations for oil and biofuel products.
Authorities made unannounced inspections Tuesday at three oil companies -- BP, Royal Dutch Shell and Statoil -- as well as Platts, a company that collects oil price data.
The European Commission said in a statement it is concerned that the companies may have worked together to report false prices and prevent others "from participating in the price assessment process." It said even small changes can hugely impact oil prices and harm consumers.
Statoil said the suspected violations could date back to 2002, and were related to the way Platts reports prices for crude oil, refined oil products and biofuels.
All of the companies said they are cooperating with investigators.
The EU said the inspections are a preliminary step in its investigation, and do not mean any of the companies are guilty.
The potential for oil price manipulation is not a new concern.
The International Organization of Securities Commissions carried out a two-year investigation at the request of the G20, which resulted last year in a series of recommendations to address potential problems and make oil price assessments more reliable.
Those recommendations included making clear the methodology for arriving at prices, adopting quality control measures for the market data being used, and instituting policies to help avoid conflicts of interest within firms.
Price reporting agencies, like Platts, have agreed to implement the principles.
Britain's Daily Telegraph quoted officials in London as saying the alleged oil price fixing could have cost individual motorists thousands of dollars over the past ten years.
The European Union has also previously fined Shell as part of a 2006 price-fixing case involving bitumen, an oil byproduct used in road construction.
The EU said in that case, Shell and 13 other companies fixed the price of bitumen in the Netherlands. It penalized Shell with the largest fine of the group, saying the company was both a leader of the plan and a repeat offender.
The investigation into the possible price manipulation follows allegations that major banks falsely reported borrowing costs to influence a key interbank loan interest rate.