Cambodia's Cabinet has approved construction of a major hydroelectric dam on a tributary of the Mekong River.

A government statement said the Cabinet gave approval at Friday's weekly meeting for the 400-megawatt hydroelectric project on the Sesan River in the northeastern province of Stung Treng.

The statement said the Lower Sesan 2 project is a Chinese-Vietnamese-Cambodian joint venture with an investment value of $781 million that is due to be completed within five years.

It said approval came after eight years of study of the possible environmental and social consequences of the project.

Critics charge that the dam would threaten the river's vitality and biodiversity, in addition to forcing the evictions of thousands of people and hurting the livelihoods of many more who are dependent on the waterway.