Copper output in Zambia, Africa's leading producer of the metal, increased by 60 percent in January as mining companies boosted production due to favourable prices, the central bank said on Wednesday.

January copper production rose to 92,958 tonnes from the 58,263 tonnes mined in the same month last year, the central bank said, while copper exports rose to 78,912 tonnes from 56,768 tonnes.

Mining companies are investing in expansion projects in order to make the most out of the favourable prices, said central bank spokesman Kanguya Mayondi.

Copper output in Zambia is expected to rise to 900,000 tonnes in 2011 from 819,159 tonnes last year as mining companies boost output.

Zambia's cobalt output dropped to 728 tonnes in January from 800 tonnes last year, while exports fell to 734 tonnes from 741 tonnes.

Mining industry sources said the drop in cobalt output could be attributed to production fluctuations because it was a by-product.

Miners operating in Zambia include Canada's First Quantum Minerals, London-listed Vedanta Resources, Glencore International AG and Metorex of South Africa.