WASHINGTON: The US Supreme Court on Monday let stand a lower-court ruling that left in place Obama administration environmental regulations limiting power plant emissions of mercury and other toxic pollutants while the Environmental Protection Agency revised them.

The justices opted not to hear an appeal by 20 states led by Michigan of a December US appeals court decision that said the rules could remain intact while the government responded to last year's Supreme Court ruling that the EPA should have considered the compliance costs when crafting the regulations.

The rules affect mainly coal-fired power plants.

Copyright Reuters, 2016