The Johannesburg-based precious metals producer is on the investor shortlist of potential buyers of the state-owned copper mines. The Zambian government had expected to have chosen the winning bidder by the end of July.

"Our involvement in the process to extend our copper portfolio into Zambia through our bid to acquire the Mopani operation is ongoing," said Sibanye CEO Neal Froneman.

"A competitive process is under way to determine the successful bidder to enter into a phase of final due diligence and exclusive negotiation on detailed terms."

The South African platinum mining giant is seeking to expand in metals that are key to the green revolution. It has already bought lithium and nickel assets in Europe and the U.S. while its domestic operations continue to be hit by rolling electricity blackouts and rising crime.

Sibanye's profit in the six months to June 30 fell 37% to 7.8 billion rand ($420.87 million), it reported on Tuesday.

Platinum and palladium output at its Stillwater operations in the U.S. dropped by 11%.

($1 = 18.5332 rand)

(Reporting by Felix NjiniEditing by David Goodman)