Labour unrest sweeping across South Africa's platinum sector hit Anglo American Platinum on Wednesday, with striking miners blockading roads leading to shafts belonging to the world number one producer, police said.

"Around 1,000 mineworkers had a confrontation with mine security last night at the Siphumelele shaft and the situation has spread to other mine shafts this morning," regional police spokesman Thulani Ngubane said.

Siphumelele is one of four mines near Rustenburg, 100 km (60 miles) northwest of Johannesburg, that have been targeted as "restructuring candidates" by Amplats parent company Anglo American.

Shares in Amplats, which has largely avoided the unrest this year that has hit rivals Impala Platinum and Lonmin, fell 3.6 per cent. Anglo American, which owns roughly 80 per cent of Amplats, shed 3 per cent.

Amplats said miners at its Rustenburg operations were "not on strike", but said it was "aware of widespread cases of intimidation".

"We confirm that yesterday, some of our employees were unable to clock in for night shift due to fear of intimidation and threats by unidentified individuals in and around our Rustenburg operations," it said in a statement.

Platinum priced in rand rose by 3.3 per cent to reach its highest level so far this year on Wednesday, boosted by the weakness in the currency and by spreading violence and unrest in the South African mining industry.

Price was up at 13,405.7 rand an ounce, its highest since mid-November, set for its largest one-day gain in a month.

Platinum has now gained more than 17 per cent since South African police shot dead 34 striking miners at Lonmin's Marikana mine, also near Rustenburg.