CHENGDU - Authorities in China's southwestern city of Mianyang Tuesday warned citizens not to drink tap water as a river that supplies water to the city was polluted by tailings of a local manganese plant.

The residues of the electrolytic manganese plant in the county of Songpan, which was administered by the city of Mianyang in Sichuan Province, were washed into the Fujiang River by heavy rains that hit the city last Thursday, according to a notice posted on the city government's official website.

According to the statement, monitors of the local environment bureau detected the pollution on Tuesday.

The city government has ordered more supply of bottled water for citizens, said the statement.

It also said that the government has been taking measures to clear the contamination in the river but it failed to elaborate on the measures.