Police have detained three senior employees of China's top gold producer Zijin Mining Group over a toxic pollution spill that has killed off vast numbers of fish, local authorities said on Friday.
The manager, deputy manager and head of environmental protection at a copper mine operated by Zijin in China's Fujian province are in custody, the Shanghang county government said in a statement.
The head of the local environmental protection bureau has resigned, while another senior official has been suspended over the July 3 spill that has contaminated the Ting river, a major waterway in Fujian.
Shares in Zijin dived 6.5 per cent to 5.16 yuan in Shanghai on Friday, outstripping falls in the broader market.
Zijin, China's third-largest copper producer, has blamed the leak from a sludge pond on rains that have pounded Fujian for the past few weeks, saying it responded immediately to the mishap and controlled the spill within 24 hours.
It has pledged to pay compensation to fish farmers who were affected. Production at the mine has also been suspended.
Investigators have found that 9,100 cubic metres of waste water leaked from the sludge pond through an "illegally built passage" into the Ting river, state media said on Friday.
As many as 1,890 tonnes of fish have been poisoned, according to previous reports.
The Ministry of Environmental Protection and local authorities have ordered Zijin to make modifications at the copper mine to prevent a further leakage, the statement said.
Years of unbridled economic growth have left most of China's lakes and rivers heavily polluted. More than 200 million Chinese currently do not have access to safe drinking water, according to government data.
Officials at Zijin were not immediately available to comment.