The Trump administration plans to loosen rules preventing oil and gas companies emitting one of the most harmful greenhouse gases.
The government proposal, expected to be announced by the Environmental Protection Agency (EPA) on Thursday, would relax requirements on oil and gas sites to monitor for methane leaks and plug them.
If it goes ahead, the move would be the administration’s latest easing of a string of environmental rules, including many made by president Donald Trump's predecessor, Barack Obama.
In 2016, Mr Obama’s EPA had issued the first rule limiting methane emissions from new oil and gas fracking operations, including transport equipment.
According to Matt Watson, vice president of the energy programme at advocacy group Environmental Defence Fund, the EPA “want to get rid of direct regulation of methane”.
Royal Dutch Shell this year urged the administration to crack down - not ease up - on the emissions.
Many others in the oil and gas industry have welcomed the easing, however.
The oil and gas business is the largest single source of methane emissions, a major factor in global warming.
The gas has more than 80 times the heat-trapping potential of carbon dioxide in the first 20 years after it escapes into the atmosphere, scientists say.
Environmentalists have vowed to sue the administration over the proposal, which would be subject to public comment before being finalised.
David Doniger, a climate and clean energy specialist at the Natural Resources Defence Council, said: “We simply cannot protect our children and grandchildren from climate catastrophe if EPA lets this industry off scot free.
“If EPA moves forward with this reckless and sinister proposal, we will see them in court.”
Agencies contributed to this report.
