SHANGHAI, China - Water supplies to 200,000 people in eastern China were cut for 40 hours due to groundwater pollution, allegedly from chemical plants, state media reported Wednesday.

Taps ran dry from Monday to Wednesday in Shuyang, a city in Jiangsu province where a massive outbreak of blue-green algae in 2005 forced the shut-off of water supplies to about 5 million people in another city, Wuxi, the official Xinhua News Agency reported.

The residential water supply from the Xinyi River had an unusual smell and was found to have levels of ammonia nitrogen far above national standards, the China Business News paper reported.

It said water was being diverted from a nearby lake to dilute the pollution, and trucks were distributing well water to ease shortages among residents.

The specific source of the pollution was not known, but the paper cited the head of Shuyang's environmental protection bureau, Hu Daolang, as blaming chemical plants upstream on the Xinyi River.

Jiangsu is a center of the Chinese chemical industry, and a massive runoff of toxic effluent has been blamed for poisoning the province's extensive grid of rivers, canals and lakes.

Chemical waste was blamed for causing May's massive algae bloom in Lake Tai near Wuxi, along with a similar bloom last month in another of the province's water bodies, Lake Chao.

In one of China's worst recent cases of river pollution, a November 2005 spill of potentially cancer-causing chemicals, including benzene, into the Songhua forced the northeastern city of Harbin to sever water supplies to 3.8 million people for five days, and strained relations with Russia, into which the poisoned waters flowed.