Waste oil discharged by a dredger hired for environmental research has polluted over seven hectares of Dianchi Lake, a scenic spot in southwest China's Yunnan Province, a local official said Thursday.

Eyewitness accounts say the dredger intentionally made the discharge on Tuesday afternoon as it wasn't fitted with the equipment to properly dispose of waste oil.  

Despite clean up efforts the pollutant spread in the water because of heavy rain and strong winds. The local administration has taken samples but results have not been released. 

The dredger was hired to collect mud from the bottom of the lake as part of an environmental protection research project by the Chinese Academy of Sciences. Those involved could be fined 100,000 yuan (US$12,500), according to the local regulations.

Dianchi Lake is the largest freshwater lake on the Yunnan-Guizhou Plateau. China has invested over 4 billion yuan (US$500 million) to solve environmental problems in the lake since the 1990s.

(Xinhua News Agency October 13, 2006)