Environmental protection and fire fighting staff in southwest China have begun cleaning a river polluted by a coal tar spill from a local chemical company.

About 80 percent of the spill on a 400-meter-long stretch of the Jiuyuan River in Tongliang County, Chongqing Municipality, had been cleared as of Sunday morning, the county government said.

The river is on the upper reaches of the Jialing River, a major tributary of the Yangtze River, China's longest waterway.

About 50 tonnes of coal tar from a tank of Jiuyuan Waterproof Materials Company based in Jiuyuan Village, flowed 100 meters into the river at around 5 a.m. Saturday, the county's Environmental Protection Bureau said.

The spill also made air in the area smell bad, but no evacuation was made.

"The strong irritating smell disrupted my sleep," said Xu Zhilan, a villager.

The bureau said it had banned residents from using water from the river.Local residents rely on wells for drinking water.

The spill has been blocked with straw, quilts and foam to avoid spreading downstream.

Environmental protection officers are continuing to investigate the cause of the leak.

The factory had stopped production before the incident, said Wang Dong, an official of Hufeng Town. The stored coal tar was due to be transferred to other areas.

(China Daily via XinhuaMay 10, 2009)