MELBOURNE - Gold Fields' CEO played down speculation that the South African gold producer is going to raise its offer for Northern Star, saying the Australian target first needs to acknowledge that it is open to a merger.

Gold Fields has embarked on a long-planned road show in Australia this month, where CEO Mike Fraser is aiming to boost its profile with investors in the country which accounts for about half of its business.

It last month lobbed a A$38.7-billion ($27.1-billion) buyout proposal in shares and cash for Perth-based Northern Star, Australia's biggest gold miner, to create the world's second-biggest producer of the yellow metal.

But Northern Star, hampered by a run of poor performance, rebuffed that offer, choosing instead its own plans for operational overhaul, pushed by activist investor Elliott Investment Management.

Both miners have gold operations in Western Australia, including around the town of Kalgoorlie where Northern Star runs Australia's biggest gold mine, known as the Super Pit.

Northern Star said in a statement that its board remained focused on acting in the best interests of shareholders.

"This includes engaging with parties on proposals that represent value above what we believe Northern Star can generate as a standalone company. The Gold Fields proposal was not in that category," it said.

Fraser said the market expected Gold Fields to make another offer.

"But I think before you get into, you know, throwing in new offers, you've got to at least have some reciprocation to say, actually we think there is a pathway (to value) here," Fraser told Reuters.

"At the moment, we're not hearing any of that."

Gold Fields has said it saw $4-billion to $5-billion in synergies, which analysts attribute mostly to tax benefits and combining operations in a Western Australian gold hub. However, one overlooked benefit was the prospect a combined company could rerate, he said.

"We absolutely believe that this combined business would be trading at a much higher relative multiple than what we're trading at today," he said.

Gold Fields' shares are trading on an enterprise multiple of 3.5 to 4 times earnings before interest, tax, depreciation and amortisation, much cheaper than Northern Star's multiple of 7 to 8 times. Larger peer, Agnico Eagle is also trading around an 8 times multiple.