The AMCU has said it is recruiting in the platinum-producing region because of the industry's low wages.

WSJ: South Africa Labor Unrest Spurs Deadly Gunbattle

According to news reports, the AMCU may call a new strike in efforts to win the right to negotiate with the company.

FORBES: Platinum Outperforming Other Metals, Lifted By South African Supply Concerns

After workers allied with the AMCU went on an illegal "wildcat strike" at Lonmin, police have unsuccessfully tried to get them to return to the mine.

WSJ: South Africa Labor Unrest Spurs Deadly Gunbattle

The stand-off is thought to have taken place between the National Union of Mineworkers (NUM) - allied to the ruling African National Congress (ANC) party - and the militant Association of Mineworkers and Construction Union (Amcu).

BBC: South African miners wounded in rival union clashes

The most recent violence at Lonmin spun from a rivalry between the emerging Association of Mineworkers and Construction Union, or AMCU, and NUM, the country's largest mine union, who are competing for majority union membership in South Africa's platinum mines.

WSJ: South Africa Labor Unrest Spurs Deadly Gunbattle