Gold Fields Ltd, the world's No. 4 gold miner, sees it net debt rising to nearly $1-billion in the near term, but then returning to the company's preferred range of $500-million to $750-million, CE Ian Cockerill said on Wednesday.

"As new (gold) projects start to come in, that will start to ease its way back," Cockerill told the Denver Gold Forum, referring to his company's debt.

"I'm not fazed on a short-term basis having debt at that level... It's not going to cause us any financial challenge, it's not going to cause us to come back to the market and ask for more money."

He also said the company planned to make a decision in December on its method for expanding its massive South Deep mine in South Africa.

Gold Fields bought South Deep last year for $2,5 billion in cash and shares to replace dwindling reserves at its other South African properties.

The mine has the world's biggest gold deposit, and promises to keep ounces flowing to Gold Fields for the next four decades.

The mine's first phase has already begun producing, but the company wants to speed up its exploitation of the second phase, which it had originally planned on mining starting in 2039.

It is currently considering four options for getting at the ore, which lies below the Phase 1 ore body.

Options include drilling horizontally from Gold Field's nearby Kloof mine, or adding additional shafts and slopes to South Deep's current infrastructure, or a combination of both.

"You don't need a calculator to tell you that accelerating production 20 years forward and adding to the existing infrastructure should give you a far better return on your capital, and that's what we're seeking to achieve," Cockerill said.

The mine holds reserves of 29 million ounces, about one-third of Gold Fields' portfolio.