The 861 km rail line, owned and operated by struggling state company Transnet, runs from Kumba Iron Ore's Sishen mine in SA's Northern Cape province to Saldanha port.

However, the line has been beset by derailments and Transnet's balance sheet "constraints" mean it is unable to run the line efficiently, said Kumba Chief Executive Officer Mpumi Zikalala.

Kumba, Africa's top iron ore miner, has scaled down production after stockpiles rose to 7.5 million metric tons last year from 7.1 million tons the previous year.

"We believe that the entire line could be concessioned to a player who will be able to purely focus on this line and that could make a massive impact," Zikalala said on a media call after Kumba reported a 45% slide in annual earnings.

Headline earnings per share dropped to $2.11 hit by lower prices and the rising iron ore stockpiles caused by lack of rail capacity, the company said.

--Reuters--