London-based BP, Europe's second-largest oil company, made the disclosure in its annual report released on Thursday.

Last May, European authorities raided offices of BP, and Royal Dutch Shell and Statoil in an investigation of suspected price manipulation.

"Related inquiries and requests for information have also been received from U.S. and other regulators following the European Commission's actions," BP said in its 2013 annual report, published on its website.

BP said it was producing documents to the U.S. Federal Trade Commission following an FTC request made in June 2013, and that the U.S. Commodity Futures Trading Commission in January 2014 had asked the company for price-reporting documents.

In addition, BP said the Japanese Fair Trade Commission made an initial request for information last June, and in December 2013, the Korea Fair Trade Commission started an investigation and a first information request was expected to be issued.

Last May, the European Commission said it was investigating major oil companies over suspected anti-competitive agreements related to submission of prices to leading oil pricing agency Platts, a unit of McGraw Hill Group.

BP said in the annual report there was no deadline for the completion of the EU inquiry. When the European action was launched, BP as well as Platts, Shell and Statoil said they were cooperating with the probe.

Thomson Reuters, parent of Reuters news, competes with Platts in providing news and information to the oil market.

(Reporting by Alex Lawler, editing by William Hardy)

By Alex Lawler