Plans to impose royalty payments on platinum miners could threaten investment in South Africa, a forthcoming report will warn.

Absa commodities specialist Hilton Ashton is due to present a paper in Johannesburg later today warning that royalty charges of around three per cent could serve as a disincentive for platinum miners.

The South African government originally proposed charges of four per cent for platinum producers, but agreed to reconsider following pressure from the mining industry.

An extract from Mr Ashton's paper published in South Africa's Business Day this morning warned: "The introduction of royalty taxation in excess of three per cent of revenue will be a significant disincentive to new investment."

"If we have royalties of three per cent or more, it will set us apart from many other countries, and I am especially concerned about the impact on platinum."

As well as platinum, the government is also planning to charge royalties for the extraction of diamonds and other precious stones.