Impala Platinum, the world's second largest platinum producer, said on Monday that a violent labour dispute at its flagship Rustenburg operations has cost it 80,000 ounces in lost production to date.

The stoppage, now in its fifth week, is costing 20,000 ounces a week but the company said its capital projects remained "largely unaffected" by the unfolding drama around the mine, where violence has claimed the lives of two miners.

The Rustenburg operations lie 120 km (80 miles) northwest of Johannesburg and are the world's largest platinum producing mines, accounting for some 15 percent of global supply.

Operations were brought to halt after over 17,000 striking rock drill operators and other mineworkers were dimissed and the rehiring process failed to secure enough mineworkers to restart the shafts.

Around 7,800 workers, including over 900 rock drill operators, have since been re-hired but the operation needs at least 2,000 rock drill operators to restart production.

Implats management said in a statement the majority of employees want to return to work, but "unprecedented levels of intimidation and violence" were preventing them from doing so.

South Africa's mines minister Susan Shabangu said the police needed to stamp out the intimidation, in her first public comments on the issue.

"I think what is happening at the Impala mine, it cannot be allowed to continue. It's not good for workers who are keen to work but are being intimidated," she said.

"We appeal to the police to take decisive action where there is intimidation," she told Reuters near the town of Ventersdorp, while visiting the family of a female mineworker who was murdered underground in an unrelated incident.

The dispute has centered on a bonus offered only part of the workforce but has escalated into a struggle between competing unions.

Implats on Monday again blamed one union, the Association of Mineorkers and Construction Union, for stirring a hornet's nest as rock drill operators reject the dominant National Union of Mineworkers (NUM).

"We have seen the emergence of a rival new union, the AMCU," Implats said.

Implats said "criminal attacks" on its property and the NUM membership had been extended to communities around the mine which have been the scene of rioting and looting.

The South Afrcan police confirmed that a second miner had been killed in a standoff on Sunday night.

Regional police spokesman Thulani Ngubane said a riot started on Sunday when 600 men went house-to-house through a township trying to force others to join them in a vandalism spree at the mine.

"Their intention was to take them to the mineshaft. The police struggled to disperse the crowd," said Ngubane. The dead man had been shot, and another was found with a bullet wound in the thigh, he added.