NANNING - A river in Guangxi Zhuang Autonomous Region has been contaminated with the heavy metal cadmium, local authorities said Friday.

The Longjiang River, located in Yizhou, Hechi city, was found to contain excessive cadimum levels by 5 pm Thursday, said a written statement released by the city government.

The cadimum amount at the Luodong Hydropower Station at the river's lower reaches was 0.0247 milligrams per liter, three times higher than the official limit, according to the environment authorities in Yizhou, the statement said.

Water tests were performed after fish kept in cages at another hydropower station at the upper reaches were found dead on Sunday, it said.

More water was discharged from the station to dilute the pollution and local villagers had been asked not to drink the river water.

The Ministry of Environmental Protection has organized a work team to visit Guangxi to investigate. The contamination source had not yet been found.

Cadmium, a chemical that is mostly found in industrial effluents, is carcinogen.