The leak Thursday at the Songchuan Chemical Co. in Anhui province's Jinzipai village was blamed on worker negligence, the official Xinhua News Agency said. The report did not say how much turpentine was discharged into the Jindonghe River.

More than 3,000 residents in the area and 1,100 elementary school students who attend a school near the river have been warned not to drink the water and are receiving water from fire trucks, it said.

Many students and residents drank the polluted water before they were informed of the incident, but there have been no reports so far of poisoning, Xinhua said, citing the local Qimen county environmental bureau.

A preliminary investigation showed that the plant had not undergone an environmental assessment and had no production permit when it began test production three months ago, Xinhua said.

Chronic pollution and chemical accidents have tainted most of China's canals, rivers and lakes, and the country is suffering from a critical water shortage.

Last month, China said it will spend 1 trillion yuan (US$125 billion; euro100 billion) to improve water treatment and recycling by 2010 to fight the mounting threat of urban water pollution.