Kinross okayed a second-phase, $590 million expansion at its Tasiast operation in Mauritania, which will help the company, the world's fifth-biggest gold miner by output, maintain production levels as some of its other shorter-life mines show declines.

The Toronto-based miner also said it will spend $445 million to add five years of production to its Round Mountain mine in Nevada, currently scheduled to end in 2022.

"These are steps in the right direction, relieving some of the pressure to make further acquisitions to maintain its current production profile," Macquarie analyst Michael Siperco said in an interview.

He said the nearly 6 percent drop in Kinross' stock was likely a "sell the news" scenario as the market had expected the projects to be approved and after the miner's stock has sharply outperformed its peers this year.

Kinross shares are up 40 percent this year, well ahead of the 3.3 percent rise in the S&P Global Gold Index <.SPTTGD>, helped by strong financial results and expectations that it can maintain it production growth at a time when some of its peers' output is declining.

Kinross' increased investment in Mauritania comes at a time when miners are increasingly seeking safe havens as a string of governments have tried to squeeze more wealth from their mineral riches.

"We feel we have a very constructive and supportive dialogue" with the government of the West African nation, Kinross Chief Executive Paul Rollinson said on a conference call, adding that the miner has been operating there for seven years with almost "no issues."

The Phase 2 expansion at Tasiast will increase the mine's annual output to 634,000 ounces at all-in sustaining costs of $720 an ounce over the project's life, Kinross said.

The expansions would allow Kinross to maintain group production at 2.5 million to 3 million ounces from 2018 to 2022, Credit Suisse analyst Anita Soni said.

Kinross plans to finance both projects with existing liquidity and operating cash flow.

The expansion at Tasiast brings some vindication for Kinross after it wrote down nearly the entire acquisition price after paying $7.1 billion for the operation in 2010 at the peak of an industry acquisition spree.

(Additional reporting by Kanishka Singh in Bengaluru and Susan Taylor in Toronto; Editing by Gopakumar Warrier and Steve Orlofsky)

By Nicole Mordant