A push for more data from China's portion of the Mekong River - which Beijing calls the Lancang River - intensified this year after U.S. government criticism that 11 Chinese dams were "hoarding" water and hurting livelihoods downstream, an accusation Beijing denies.
"This agreement is a landmark in the history of China-MRC cooperation," An Pich Hatda, the MRC Secretariat Chief Executive Officer, said in a statement.
He added that data-sharing is critical to the management of the Mekong, on which 60 million people depend for fishing and farming in downstream countries Thailand, Cambodia, Laos and Vietnam.
Two years of record drought on the 4,350-km (2,700-mile) waterway have severely harmed livelihoods and raised questions over how mainstream Mekong dams in China and downstream in Laos were affecting the flow of water.
China has for 18 years shared water during the June to October monsoon season with the MRC - an advisory body to member countries Thailand, Laos, Cambodia and Vietnam - to provide early flood warnings.
However, with drought an increasing concern, the MRC has been seeking year-round data to help analyse what may be causing the river's low flow.
China's prime minister in August pledged to provide more data, but it previously had been unclear whether it would come through Beijing's own Lancang-Mekong Cooperation body or the 25-year-old MRC.
The new agreement will see China provide year-round data from two hydrological stations in Yunnan Province, including rainfall and river level data, the MRC said.
China also agreed to report any unusual rise or fall in water levels, it said. - Reuters