The victims did not suffer serious symptoms, the official Xinhua news agency reported, but the poisoning in Ruyang county in central China's Henan province affected the water supply to more than 9,000 homes.

Police investigating the cause of the poisoning found the county's water supply had been tainted by pesticide, Xinhua said.

Initial investigations revealed pesticide had been thrown into the local reservoir, Xinhua quoted Chai Zhanxian, deputy local police director as saying.

Officials were investigating to determine whether the contamination was deliberate and the local water supply facility had been shut down.

TERRA.WIRE