Marginal platinum projects in South Africa are under threat because of government plans to introduce royalty charges.

Ralph Havenstein, chief executive of platinum producer Anglo Platinum, has warned that some projects could close if the charges are introduced.

The South African government is currently consulting on plans to charge foreign mining companies royalties of around four per cent.

"The mining industry believes the imposition of royalties on revenue would be detrimental for marginal mines, and for new development," he told Business Day.

"It would certainly have an impact on a marginal project. The mining industry would argue for a profits-based royalty."

His comments follow a report from Absa commodities specialist Hilton Ashton, warning that royalties would jeopardise future investment in South Africa.