BEIJING, Aug 4 (Reuters) - Nearly eight out of 10 Chinese coastal city sewers discharged excessive amounts of pollutants into the sea in the first six months of the year, state media said on Saturday.

Most of the outlets were "improperly arranged", Xinhua news agency said, with 43 percent in tourist, sea farming and other reserved areas and 33 percent in harbour and shipping areas.

Rapidly growing China is poised to overtake the United States as the world's top emitter of greenhouse gases, and Beijing faces rising international calls to accept mandatory caps on carbon dioxide emissions from factories and vehicles.

Water pollution has become a hot political issue in China, especially with the 2008 Beijing Olympics just a year away, after a series of algae outbreaks in freshwater lakes across the country in recent months.

Algae blooms develop in water that is rich in nutrients, often because of run-off from heavy fertiliser use, industrial run-off and untreated sewage -- all pollutants in ready supply in many parts of China.

A report by the State Oceanic Administration said 77 percent of coastal sewers were discharging more pollutants than allowed. It said 82.8 percent of sewer outlets along east China's Yellow Sea discharged excessive pollutants.

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