China's top environmental watchdog launched investigations into six of the country's most notorious polluters on Friday, with last week's chemical spill on a tributary to the Songhua River on the list.

The Changbaishan Jingxi Chemical Company illegally dumped about10 cubic meters of chemicals into the Mangniu River in northeast China's Jilin Province at midnight of Aug. 20, resulting in a five-kilometer-long pollution slick of reddish xylidine.

The chemicals did not enter the Songhua as the stretch of polluted water had flowed into the Songhua River after undergoing filtration and other control measures, according to SEPA.

Chinese authorities have closed the factory and detained seven suspects following the spill, according to SEPA's official Lu Xinyuan.

Other targets of SEPA's investigation include Harbin Gasification Factory in northeast China's Heilongjiang Province, which has failed to carry out the environmental impact assessment (EIA) since it was set up in 1992 and has continued discharging wastewater containing excessive amounts of pollutants.

The county government of Xin'an in central China's Henan Province has allowed the construction of more than 100 factories with no waste-treatment facilities since 1998.

The municipal government in Jinhua in east China's Zhejiang Province, allegedly interfered with the enforcement of environmental laws.

The Yili Prefecture in northwestern China's Xinjiang Uygur Autonomous Region is held responsible for the discharging of massive quantities of industrial pollutants.

And Jinmao Papermaking Ltd. Co. in Langfang in north China's Hebei Province failed to pass the EIA test due to the lack of a required sewage treatment facility but attempted to start operations without permission in May 2006.

"The ongoing probe will zero in on offences by governmental offices and law enforcement officers," Sun Huaixin, deputy director of the law enforcement department of the Ministry of Supervision, was quoted by China Daily as saying.

(Xinhua News Agency September 2, 2006)