China is ready to start building a series of controversial hydropower plants on the Nu River in the southwestern province of Yunnan, state media said, citing a senior energy official.

We believe the Nu River can be developed and we hope that progress can be made.. during the 12th Five-Year Plan period (2011-2015), Shi Lishan, the deputy director of new energy at the National Energy Administration (NEA), told Chinese national radio.

The construction of dams and reservoirs on the UNESCO-protected Nu River -- also known as the Salween -- was first proposed in 2004, but disputes among China's leadership and opposition from both Chinese and southeast Asian environmental groups has delayed the projects.

The Nu River, which begins in the Himalayas and snakes its way along the far western edge of Yunnan before entering Myanmar and Thailand, is one of the few major Chinese rivers yet to be dammed. The Chinese government says total potential capacity on the river could stand at 42 gigawatts.

The construction of big hydroelectric projects slowed in China after the completion of the world's largest facility at the Three Gorges on the Yangtze River, with China's leadership wary about the costs of relocating thousands of displaced residents as well as the environmental impact of massive reservoirs.

But with China committed to increasing the share of non-fossil fuels in its total energy mix to 15 percent by 2020, there have been signs that the tide is turning, and the Nu River is one of a number of potential new projects now back on the agenda.

Last November, the official China Securities Journal said that a pledge to dam the Nu River was likely to be included in China's latest five-year plan for the renewable energy sector.

The plan is also expected to include a commitment to accelerate dam construction on the Jinsha River, the upstream section of the Yangtze also situated in Yunnan province.

China plans to build an additional 140 gigawatts of hydropower capacity in the next five years, the NEA revealed earlier this month.