China plans to build a dozen hydroelectric power plants in the next 20 years with an installed capacity totalling 90.2 million kilowatts, media reported.

The projects will be built on the upper reaches of the Yangtze River, known as the Jinsha River, and on two upstream Yangtze River tributaries, known as the Yalong and Dadu rivers, Xinhua news agency reported.

It quoted Cao Guangjing, deputy manager of the China Three Gorges Project Development Corporation, who said the installed capacity of each hydropower plant on the Jinsha, Yalong and Dadu will range from 1 million to 10 million kilowatts.

Construction of two of the plants, the Xiluodu and Xiangjiaba hydropower plants, has already begun on the Jinsha river and will have a combined installed capacity of 18.6 million kilowatts when completed, he said.

Cao's statements come despite heightened environmental concerns over building so many hydroelectric dams on the Yangtze and its tributaries. The central government is rethinking the ambitious plan and urging environmental impact studies for all projects.

China boasts the world's greatest hydropower resources with a theoretical potential of 680 million kilowatts, Xinhua said.

Hydropower will help ease the nation's huge dependence on coal use which not only pollutes the air, but causes acid rain and global warming.

Last week the government gave the go-ahead for the Baihetan project, which will have an installed capacity of 12 million kilowatts and is also located on the Jinsha river.

The Baihetan dam will be China's third largest hydroelectric project -- behind the Xiluodu hydropower station, which is designed to have a capacity of 12.6 million kilowatts and the Three Gorges Dam that will have a capacity of 18.2 million kilowatts.

The Three Gorges dam was officially completed last month, marking a milestone in China's effort to tame the Yangtze, although more power generators need to be installed to make it fully operational.