Gold and copper production in China may suffer a setback following the Chinese government's order to limit Zijin Mining Group's production at a gold mine located near a separate copper mine that was the source of a toxic spill.

Poisonous waste water from the copper mine in Fujian province operated by Zijin - China's top gold producer - contaminated a major river earlier this month, killing off nearly 2,000 tonnes of fish.

The output limits imposed by local authorities on the nearby Zijinshan Gold Mine aimed to prevent further environmental risks, said a company statement.

Zijin, whose gold output was 75.4 tonnes in 2009, estimated production would be reduced by about one tonne this year due to the limit.

Zijin said earlier that police had detained three executives over the spill and the securities regulator had launched an investigation into the company over possible violation of information disclosure rules.

The leak took place on July 3 but was only disclosed by the company nine days later. Zijin had already been ordered to halt production and make modifications at the copper mine. Zijin Mining produced 75.37 tons of gold in 2009, an amount 31.05% more than in 2008, and the firm's profits from gold business hit RMB 5.02 billion last year, accounting for 35.95% of the total RMB 13.96 billion all the Chinese gold firms reaped in 2009.