Three managers of a copper plant have been detained and four local officials have been suspended from work or resigned after the plant was blamed for contaminating a river in Shanghang County in east China's Fujian Province.

Lin Wenxian and Wang Yong, head and deputy head of the plant, which is owned by the Zijin Mining Group Co, a leading gold producer in China, as well as Liu Shengyuan, who was in charge of the plant's environmental protection, have been detained, said Wen Songxing, commissar of the Shanghang county public security bureau, at a press conference on Thursday night.

Chen Jun'an, head of the county's environmental protection bureau, Lan Fuyan, deputy head of Shanghang County and Lin Lianjing, director of the environmental protection bureau of Longyan, which administrates Shanghang, resigned in the wake of the river pollution, China Central Television (CCTV) reported on Friday.

Qiu Heqing, head of Shanghang County government, has been suspended from work while the case is still being investigated, CCTV reported.

Pollutants from the copper plant have severely contaminated the Tingjiang River, killing fish in large quantities, according to an official probe.

A joint investigation conducted by the Fujian provincial and Longyan City environmental protection authorities concluded that wastewater leaks had occurred in a number of the plant's tanks, including a sewage tank, due to poor maintenance.

The persistent heavy rain in the past weeks caused the impermeable seal of the sewage tank to burst, spewing a large quantity of wastewater into the river.

A total of 9,100 cubic meters of wastewater spewed from the blown-out sewage tank and passed through an "illegally built passage" into the Tingjiang River early this month, the investigation revealed.

The investigation also found the "passage" was dug through the impermeable wall of the surveillance tank, which sits right next to the sewage tank and had been built to monitor and collect the any leaked wastewater.

Investigators said the company and local environmental protection authorities failed to detect the pollution promptly because the water quality monitoring facilities set up in the lower reach of the Tingjiang River were damaged.

The county's public security bureau has launched a further investigation into the incident to decide on management culpability and a penalty in line with damages.

Shares for Zijin Mining dropped by 6.52 percent to close at 5.16 yuan (US$0.76) in the Shanghai bourse by midday Friday.

Meanwhile, the plant has been ordered to suspend production until it permanently blocks leakages in all its tanks.

Copper production at Zijinshan copper plant accounts for about 15 percent of Zijin's annual output, Guotai Junan Securities Co said.

In the wake of the incident, Fujian province has promised to immediately start an operation to cull out potential hazards that could threaten the environment.

(Xinhua News Agency July 16, 2010)