Copper output in Africa's No.2 producer of the metal dropped to 593,500 tonnes between January and September 2021 from 623,816 tonnes in the corresponding period of last year, Kabuswe said.

"The decrease is due to operational challenges at Kalumbila, Lumwana and Lubambe mine," Kabuswe said.

(Reporting by Chris Mfula; Editing by Promit Mukherjee)