European officials are investigating some of the world's biggest oil companies on suspicions of price manipulation over more than a decade.
Shell, B-P and Statoil all say they're co-operating with the European Commission.
The commission carried out unannounced inspections on Tuesday, because of concerns the companies may have worked together in reporting distorted prices.
The investigation is centered on reporting at Platts -- the market leader in providing oil benchmark figures.
The European Commission says even small distortions could have a huge impact worldwide on prices of crude oil and gasoline.