WASHINGTON (Reuters) - The Supreme Court on Monday rejected a global warming lawsuit against five big power companies, its most important environmental ruling since 2007 and a victory for the utilities and the Obama administration.

The justices unanimously overturned a ruling by a U.S. appeals court that the lawsuit now involving six states can proceed in an effort to force the coal-burning plants to cut emissions of gases that contribute to climate change.

(Reporting by James Vicini, Editing by Doina Chiacu)