KUNMING, Oct. 12 (Xinhua) -- Over seven hectares of Dianchi Lake, a scenic spot in southwest China's Yunnan Province, have been polluted by waste oil discharged by a dredger hired for environmental research, a local official said on Thursday.

Eyewitness accounts say that the dredger intentionally poured the oil into the water on Tuesday afternoon as it failed to be equipped with the device to dispose of the waste oil it had accumulated.

Despite efforts to clean up the oil, the pollutants dissolved and spread in the water due to heavy rain and strong winds. The local administration has sampled the water but no results have 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. It could be fined 100,000 yuan (12,500 U.S. dollars), according to the local regulations.

Dianchi Lake is the largest freshwater lake on the Yunnan-Guizhou Plateau. China has invested over 4 billion yuan (0.5 billion U.S. dollars) to solve environmental problems in the lake since the 1990s. Enditem