BEIJING- China will look into methane emissions in key industries, including coal mining, agriculture and petroleum, and publish a nationwide methane emission control action plan, the environment ministry said on Thursday.

China and the United States, the world's two biggest greenhouse gases emitters, unveiled a deal earlier this month to ramp up cooperation tackling climate change, including by cutting methane emissions. 

"The formulation of a methane action plan is ... an important work of China's active response to climate change strategy, and an important measure to implement the Sino-U.S. joint declaration," Lu Xinming, a vice director of the climate change department at the Ministry of Ecology and Environment (MEE), told a news briefing.

Methane is emitted during energy production, raising livestock and the decay of organic waste in landfills. It is more short-lived in the atmosphere than carbon dioxide but 80 times more potent in warming the earth.

China's methane emissions were 55.29 million tonnes in 2014, accounting for 10.4% of total greenhouse gases emission in the country, latest official data has revealed. The energy sector contributed 45% of the methane discharge while agriculture accounted for 40%.

"We will roll out thorough research on China's methane emission control situation, and set effective emission reduction measures targeting coal mining, agriculture, solid waste and sewage water treatment, as well as petroleum and natural gas sectors," Lu said.

Lu also said the MEE will set standards for the reduction and utilisation of methane emissions at coal and petroleum industries, and will encourage companies to cut methane emissions via market trades.

China has a carbon emissions trading platform, but not one for methane.

The MEE did not disclose the time frame and detailed targets of the nationwide methane reduction action plan. But an MEE official, who declined to be identified as he is not authorised to speak to media, said the plan was scheduled to be published in 2022.

Some Chinese oil and gas firms, such as China National Petroleum Corp and Sinopec, have set their own targets on cutting methane emissions. 

(Reporting by Muyu Xu and Dominique Patton; Editing by Jacqueline Wong) ((muyu.xu@thomsonreuters.com; +86 10 56692117;))