Raids were also conducted at the London office of price-reporting agency Platts and the Stavenger office of Norway’s Statoil.
Prices reported by agencies such as Platts are used as the benchmarks for trade in a huge number of products, including the petrol price.
The suspected violations are related to Platts’ Market-On-Close (MOC) price assessment process, which is used to report prices for crude oil, refined oil products and biofuels.
In a statement EC said, "Investigators carried out unannounced inspections at the premises of several companies active in and providing services to the crude oil, refined oil products and biofuels sectors."
"The Commission has concerns that the companies may have colluded … to manipulate the published prices for a number of oil and biofuel products," EC added.
"Even small distortions of assessed prices may have a huge impact on the prices of crude oil, refined oil products and biofuels purchases and sales, potentially harming final consumers."
The commission noted that the raids were an initial step to investigate suspected anti-competitive practices.
Oil & Gas UK’s chief executive Malcolm Webb said, "Oil & Gas UK notes that the EU Commission has launched an investigation into European oil prices."
"We look forward with interest to the results of this inquiry but pending that or evidence of malpractice on any company’s part, it is not sensible for us or others to prejudge the outcome," Webb added.
