Muswellbrook is among Australia's top methane hotspots, according to a new national inventory of greenhouse gas emissions.
Preliminary data from the monitoring platform Open Methane - which uses satellite-based measurements and ground-based verification to track emissions - estimates methane levels could be twice as high as what are currently reported.
It also shows that emissions from gas and coal projects could be worse than thought.
Australia's 20 highest emitting locations, which include Muswellbrook, were all linked to coal or gas extraction, suggesting these sectors could be producing as much methane as the agriculture industry, if not more.
Methane is believed to account for 30 per cent of the world's temperature rise since the industrial revolution.
It is "turbocharging" heatwaves, bushfires and other extreme weather events in Australia, Australian Conservation Foundation campaigner Piper Rollins said.
"Climate-heating methane emissions from Australia's coal and gas sector are being massively underestimated," she said.
Lock the Gate national coordinator Ellen Roberts said the implications of the methane data for the Australian government were stark.
"Australia has perilously higher methane emissions than we thought, is at risk of burning up its emissions goals and must take action to prevent the coal mining industry from driving dangerous levels of global warming for which all Australians will pay the price," she said.
"The agricultural and land sectors that have provided most of Australia's emissions abatement in the last twenty years will bear the brunt of climate change damage and are still expected even now to deliver carbon offsets to expanding coal mines emitting god knows how much dangerous methane. This is a recipe for disaster.
"There is no time to continue business as usual while these wild data anomalies are fixed: if it is to have any credibility on climate change, the government must halt any further expansion of coal mining and insist that existing mines take immediate action to reduce methane pollution."
Methane emissions from the energy sector remained near a record high in 2023 despite commitments from the oil and gas industry to plug leaking infrastructure.
However, the International Energy Agency said it was optimistic new satellites could help improve monitoring and transparency around leaks of methane.
"Emissions from fossil fuel operations remain unacceptably high," said IEA chief energy economist Tim Gould, although he added that 2024 could mark a "turning point."
Production and use of fossil fuels put more than 120 million metric tonnes of methane into the atmosphere last year, the agency's report said -- a slight rise over 2022. Methane emissions have held around this level since 2019, according to the IEA's Global Methane Tracker.
