"Present forecasts are that copper production, both concentrate and finished copper, will now be drastically lower than last year, and could be as much as 100,000 tonnes lower," it said in a statement.

Referring to tax changes the mining industry says will stymie investment, it said the 2019 tax regime was "forcing miners to do the unthinkable – to cut production – because many cannot afford to continue producing as before".

Last year's output was 861,946 tonnes, the chamber said.

(Reporting by Chris Mfula, writing by Barbara Lewis; editing by Jason Neely)