WASHINGTON (Reuters) - The U.S. Senate budget committee on Thursday launched a probe of 18 domestic oil producers about any efforts to illegally coordinate with the Organization of the Petroleum Exporting Countries on oil prices.

Senator Sheldon Whitehouse, a Democrat and the chairman of the committee, said in a statement he seeks to understand whether oil producers operating in the U.S. have coordinated with OPEC, and a wider production group called OPEC+ that includes Russia, on oil output, crude oil prices and "the relationship between the production and pricing of oil products."

The producers that the committee is probing include Exxon Mobil, Chevron and ConocoPhillips. None of those companies immediately responded to requests for comment.

(Reporting by Timothy Gardner, Editing by William Maclean)