Policy analysts called the plan vague and disappointing. Producing more than 14% of global methane emissions, China is by far the biggest methane emitter.

Beijing released its plan near the end of a four-day climate meeting between China and the United States, pledging to "effectively improve" its monitoring and supervision systems for methane in its five-year plan period through 2025, and to "significantly improve" those systems in 2026-2030.

The country will also strive to curb "flaring," or burning off emissions, at oil and gas wells, while targeting methane leaks at coal mines to be closed up, according to the plan published by China's Ministry of Ecology and Environment.

And it vowed to promote methane control in agriculture and to strengthen methane controls from waste.

In a statement, the president of this year's COP28 climate summit, Sultan Al Jaber, welcomed the announcement as "a critical step for global climate action."

Policy analysts were less enthusiastic. Having waited two years for the plan after China pledged at COP26 in Glasgow to cooperate with the U.S. on measuring and reducing methane, the analysis said the resulting strategy left much unaddressed.

"The objectives mentioned in the plan are too ambiguous, and contain mainly descriptive text, no specific targets in methane emissions reduction," said Yan Qin, lead carbon analyst at Refinitiv, a part of LSEG that provides global financial market data.

Tackling methane emissions is seen as a key way of controlling climate change in the short term, as its warming potential is 100 times that of carbon dioxide. It also dissipates within years from the atmosphere, compared with CO2 lasting up to 1,000 years. That means reducing methane emissions can have a rapid impact in slowing global warming.

China has not joined a global pact signed by more than 150 countries to cut their methane output 30% by 2030.

While China's plan does not include targets for reducing methane, it does envision capturing and using more of those emissions as fuel.

It says it will aim to use 6 billion cubic metres (7.9 million cubic yards) of methane gas released from coal mines by 2025, and will aim for collecting what it describes as an "international advanced level" of these emissions from oilfields by 2030.

China's methane plans have been a key part of negotiations with the United States to find common ground ahead of COP28, with the Chinese climate envoy Xie Zhenhua meeting this week with U.S. counterpart John Kerry in California.

The State Department did not immediately respond to a request for comment on the plan.

Climate analyst Li Shuo, incoming director of the China Climate Hub at the Asia Society, told Reuters that the plan's release potentially "paves the way" for a joint statement from the world's two largest greenhouse gas emitters in coming weeks.