SOUTH African police fired teargas and rubber bullets to disperse striking miners at a gold mine near Johannesburg on Monday, the latest outbreak in a wave of labour militancy spreading from platinum mining into other parts of the sector.
The unrest occurred less than three weeks after police shot dead 34 striking miners at Lonmin's Marikana mine, the deadliest security incident since the end of white-minority rule in 1994.
The Marikana shooting shocked South Africa and marred the image of the continent's biggest economy, as the full extent of a breakdown in labour relations in the mining sector became apparent.
World platinum prices have risen more than 10 percent since the shooting.
In Monday's incident, mine owner Gold One International Ltd said about 60 workers at its Modder East site went on a wildcat strike, blocking half its employees from reporting for their shifts.
"The group, however, refused to disperse. The South African Police Service had to use teargas and rubber bullets to disperse the group," it said in a statement.
Police spokeswoman Pinky Tsinyane said four people were injured in the incident, which she described as a "shoot-out" between protesting ex-miners, miners and security guards.
"Police are investigating a case of attempted murder," she said, adding that four arrests had been made. "We understand that the ex-miners were assaulting the miners who were coming to work this morning."
In a separate dispute - but one born of similar social conditions - an illegal strike involving a quarter of the 46,000-strong workforce at the KCD East gold mine, owned by world No. 4 bullion producer Gold Fields, entered its third working day.
The Marikana unrest stemmed ultimately from a turf war in the platinum sector between the dominant National Union of Mineworkers (NUM) and the small but militant Association of Mineworkers and Construction Union (AMCU).
The government has been trying to broker a peace accord to cool off the feud before it does lasting damage to the platinum industry and spreads across a sector that accounts for 8 percent of South African output.
On Monday, the first of 270 miners detained at the Marikana shootings were released from police custody after prosecutors withdrew murder charges brought under an obscure apartheid-era security law for the police killing of their colleagues.
The public outcry at the murder charges soured the already testy relationship between the unions, Lonmin management and the government, which has been trying to put a lid on the mess and end a wildcat strike approaching its fourth week.
Labour Minister Mildred Oliphant, part of a committee trying to broker an end to the dispute, raised hopes of a breakthrough by saying management and workers had agreed in principle to sign a two-year wage agreement.
But unions involved in the talks said a return to work was by no means certain.
"I don't share the same optimism," said Gideon du Plessis of the Solidarity trade union. "The workers have made it clear that they will not go back to work until such time that their wage demands are met."
Lonmin shares in Johannesburg rose nearly 4 percent on hopes of a speedy resumption of mining, but lost most of those gains as hopes of a breakthrough faded. Lonmin said only 4.5 percent of its shift workers turned up on Monday.
"An indefinite strike will ultimately threaten the jobs of more than 40,000 workers. We cannot go on indefinitely without normalising operations and still escape the consequences of the mine not being operational," it said in a statement.
Many of the AMCU-affiliated miners have accused the NUM of caring more about its political connections to the ruling African National Congress than about the plight of workers deep underground.
The 3,000 striking Marikana workers are mostly rock drill operators demanding 12,500 rand ($1,500) a month in basic wages, more than double what they receive now.