WASHINGTON (REUTERS) - The US Supreme Court on Thursday (June 30) imposed limits on the federal government's authority to issue sweeping regulations to reduce carbon emissions from power plants in a ruling that will undermine President Joe Biden's plans to tackle climate change.

The court's 6-3 ruling restricted the Environmental Protection Agency's (EPA) authority to regulate greenhouse gas emissions from existing coal- and gas-fired power plants under the landmark Clean Air Act anti-pollution law. Biden's administration is currently working on new regulations.

The court's six conservatives were in the majority, with the three liberals dissenting.

The justices overturned a 2021 decision by the US Court of Appeals for the District of Columbia Circuit that had struck down Republican former president Donald Trump's Affordable Clean Energy rule. That regulation would impose limits on a Clean Air Act provision called Section 111 that provides the EPA authority to regulate emissions from existing power plants.

The Supreme Court's conservative majority has signalled ongoing scepticism towards expansive federal regulatory authority.

The case was centered around Trump's Affordable Clean Energy rule intended to impose limits on a Clean Air Act provision called Section 111 that provides the EPA authority to regulate emissions from existing power plants.

A group of Republican-led US states led by major coal producer West Virginia asked the justices to limit the EPA's ability to regulate greenhouse gas emissions from existing power plants under the Clean Air Act. Other challengers included coal companies and coal-friendly industry groups. Coal is among the most greenhouse gas-intensive fuels.

Democratic-led states and major power companies including Consolidated Edison Inc, Exelon Corp and PG&E Corp sided with President Joe Biden's administration, as did the Edison Electric Institute, an investor-owned utility trade group.

The Biden administration wants the US power sector decarbonised by 2035. The United States, behind only China in greenhouse gas emissions, is a pivotal player in efforts to combat climate change on a global basis.

The United Nations on Feb 28, the same day as the Supreme Court's oral arguments in the case, released a 3,675-page report urging global action to combat climate change.

The rule proposed by Trump, a supporter of the US coal industry who also questioned climate change science, was meant to supplant Democratic former president Barack Obama's Clean Power Plan mandating major reductions in carbon emissions from the power industry.

The Supreme Court blocked Clean Power Plan implementation in 2016 without ruling on its lawfulness.

The decision was issued on the final day of rulings for the court's current nine-month term.