NANNING - A mining firm has been held responsible for discharging waste, contaminating the Longjiang River in Southwest China's Guangxi Zhuang autonomous region, local authorities confirmed Wednesday.

Supervised by the Ministry of Environmental Protection and the regional government, authorities in Hechi city, home to the polluted section of the river, have verified the cadmium pollutants were discharged by the Guangxi Jinhe Mining Co Ltd.

The city government has not yet announced penalty measures.

Excessive cadmium levels were detected in the Hechi section of the Longjiang River on Jan 15, the deposits killing fish and prompting concerns over drinking water.

The cadmium density of a water sample taken at the Luodong Hydropower Station at the river's lower reaches on Wednesday was 0.0037 milligrams per liter of water, as compared with Saturday's sample test result of 0.0247 milligrams per liter, three times higher than the official limit, according to the city's environment department.

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

Over the last week, the local fire department put 80 tons of neutralizers, made from dissolved aluminum chloride, into the Longjiang River to dissolve the contamination.

The incident caused panic buying of bottled water in Liuzhou city at the lower reaches of the river over the past few days. However, city authorities have taken proper control of the situation by publishing real-time water sample test results via local media and ensuring the prices and market supply of bottled water.