Thailand has spiked Chinese-led plans to open up a key stretch of the Mekong river, in a rare victory for activists fighting to preserve Southeast Asia's most important waterway.
Beijing has long wanted to blast 97 kilometres (60 miles) of rocks and dredge the riverbed in northern Thailand to open up a passage for massive cargo ships.
The vision is to create a river trade link from China's Yunnan province thousands of kilometres south through the Mekong countries -- Myanmar, Laos, Thailand, Cambodia and Vietnam.
But environmentalists warn the river -- the world's most biodiverse after the Amazon -- would be ruined by dredging, while Thailand's sovereignty and security could also be compromised.
The Thai cabinet announced Tuesday it had decided "to stop the project" after Beijing failed to stump up the money for further surveys of the area to be dredged.
"This is a bold decision made by a downstream country," said Pianporn Deetes of advocacy group International Rivers, which has backed a near 20-year grassroots campaign to preserve the key stretch of water.
"This small part of the Mekong river will also save the lower part of the basin from destruction, despite large pressures from a regional actor."