The Hezhou city government in the Guangxi Zhuang autonomous region confirmed the Huiwei ore treatment factory in a suburb of the city is the main party responsible for thallium and cadmium pollution of the Hejiang River.

The pollution, which started on July 1 and will last for a couple of weeks according to experts, affects about 30,000 people living in the downstream Fengkai county of Guangdong province and has forced all water supply plants in downstream regions in Guangdong to take emergency action.

The Huiwei factory is suspected of changing its production technology without permission and secretly discharging cadmium- and thallium-contaminated wastewater into a branch of the Hejiang River.

The person in charge of the factory's production, identified as Gong, has been detained and the factory's workshops and production equipment have been closed down.