China has been extremely cautious about building hydropower projects on the Nu River, or the Salween, in the southwestern Yunnan Province, Yunnan's Party chief Bai Enpei said Wednesday.

He said no decision concerning hydropower development would be made until all factors and possible consequences are thoroughly investigated and considered.

"Central and (Yunnan) provincial governments have always been very, very cautious about hydropower projects. The Nu River is no exception," said Bai, secretary of Yunnan provincial committee of the Communist Party of China.

"We have to conduct thorough researches on ecological and environmental factors, as well as on impacts on countries in the lower reaches of the river," Bai, also a national lawmaker, said in Beijing.

"Only after we fully consider all these factors and are sure they can be properly dealt with, can we decide if we should start the project," he said.

The Nu (Salween) River, about 3,000 km long, flows southward from southwest China's Qinghai-Tibet Plateau, through Yunnan and Myanmar, into the Andaman Sea.

Bio-diversity and environment in the upper reaches of the river is considered highly valuable but fragile, which has resulted in heated debates over hydropower development on the river.