Even so, First Quantum on Tuesday flagged rising costs on the back of higher Zambian royalty rates driven by increased copper prices.

"There has been limited progress" on talks with the Zambian government for terms which would pave the way for an expansion of ore processing at Kansanshi ahead of national elections, Pascall said.

Zambian President Edgar Lungu faces his most serious challenge yet from businessman and serial presidential hopeful Hakainde Hichilema in elections set for August 12.

Zambia's ZCCM-IH sealed its acquisition of Mopani Copper Mines in March giving the state a deeper understanding of mine operations, Pascall said.

"We don't see any significant risk there given where tax rates are at the moment," he said.

(Reporting by Jeff Lewis; Additional reporting Chris Mfula in Lusaka; Editing by Mike Harrison)

By Jeff Lewis