Harmony is staking its future on the $4.8 billion project it is developing with Australian group Newcrest Mining (NCM.AX).
Papua New Guinea has the right to a 30 percent stake in mining operations. Harmony chief executive Graham Briggs said on Wednesday if the government exercised this option it would include development costs already forked out.
The gold and copper project's prefeasibility study estimates an initial mine life of 26 years with annual production of 490,000 ounces of gold and 290,000 tonnes of copper.
The aim is to start production in 2019.
Briggs said it was difficult to say whether the government was in a position to pay for the stake but he said discussions with ministers suggest they see the project as generating significant growth for the region.
"This is certainly a game changer in Papua New Guinea, it could add considerable amounts to the GDP and there are lots of opportunities for the government to leverage off this," he said.
NO FUNDING SEEN REQUIRED BEFORE 2017
Results of the prefeasibility study peg the cost of establishing a copper-gold development at around $4.8 billion, which will be shared evenly by Harmony and Newcrest.
Chief Financial Officer Frank Abbott said the firm would consider debt or bonds to top up its capital expenditure needs as the production of its Papua New Guinea operations gets nearer.
"We don't see the need for additional funding until 2017 and then it will depend on the gold price," Abbott said.
He indicated that if the gold price remained in the $1,600 an ounce range, the company would need to raise 4 billion rand ($475 million) but if it dipped to $1,400 an ounce it would require almost double or 7 billion rand ($832 million). Spot gold is currently fetching about $1,665.00.
The project is a game changer for Harmony as it diversifies production away from high-cost and politically-risky South Africa, where labor violence in the platinum belt has killed 44 people this month.
The company currently gets 90 percent of its output from South Africa and aims to lift production to 1.7 million ounces by 2016 from a target 1.3 million ounces in 2013.
($1 = 8.4155 rand) (Reporting by Sherilee Lakmidas; editing by Ed Stoddard and Mark Potter)