President Trump is planning to relax regulations governing methane emissions in the oil and gas industry, according to reports, in a move that could allow millions more tonnes of warming gases to be released into the atmosphere each year.
Under the changes oil and gas producers would no longer have to implement systems to spot and fix methane leaks.
The rule change, which has been expected for months, will be confirmed by the US Environmental Protection Agency (EPA) before Friday, US media reported.
The EPA argues the change is needed to relieve pressure on a beleaguered oil and gas industry hit hard by the coronavirus pandemic.
But campaign group the Environmental Defense Fund warns the changes could result in an additional five million tonnes of methane pollution every year. Methane is a greenhouse gas many times more powerful than carbon dioxide.
Even some oil and gas companies are nervous about the rollback, with larger firms such as BP and Shell repeatedly expressing their support for federal regulations on methane. They are worried Mr Trump’s bonfire of green regulations will harm the reputation of their industry.