Statoil said its headquarters in Stavanger were searched by European and Norwegian regulators looking into potential violations of anti-competitive agreements.
"The suspected violations are related to the Platts' Market-On-Close price assessment process, used to report prices in particular for crude oil, refined oil products and biofuels, and may have been on-going since 2002," the company said in a statement.
Traders report transactions to Platts, which publishes prices used to set costs that refiners pay for crude oil. The European investigation extended to, but wasn't limited to, BP and French supermajor Total, which as much as 80 percent of crude oil transactions are determine by prices like those published by Platts, Bloomberg News reports.
"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 European Commission said in a statement.
McGraw Hill, the parent company of Platts, was sued by the U.S. government this year in connection to bond risks tied to the global financial crisis, Bloomberg reports. There was no statement on the European investigation from McGraw Hill or Platts.