BEIJING (AP) _ China will shut 50 more factories along the Yangtze River to boost environmental protection around the world's largest hydroelectric project, state media reported Saturday.

More than 150 paper mills and tanneries have already been closed in hopes of stopping pollution around the Three Gorges Dam site, the Xinhua News Agency reported.

Environmental officials in Chonqing, the sprawling city that will sit at the head of the dam's reservoir, said the 50 cement plants will be closed because they ``have caused serious air pollution and water quality problems'' Xinhua reported.

An unnamed official cited by the news agency said any other polluters will be shut down ``without hesitation.''

When the dam is completed in 2009, more than 80 percent of the mammoth reservoir lies within the Chongqing area, now China's largest municipality.

Chinese leaders are determined to see the $24.6 billion dam succeed, despite criticism by environmentalists and human rights groups that it is too costly and too intrusive for forcing the relocation of a million people.

China's legislature, the National People's Congress, has already called for areas in the Yangtze basin to step up efforts to reduce soil erosion, which was exacerbated by this summer's heavy flooding, the China Daily reported Saturday.