South African police and security guards fired rubber bullets and tear gas Monday at sacked gold miners who were attacking colleagues to block them from working, the mine owner said. Police said four people were wounded at the mine that used to be partially owned by the president's nephew.

The clash at the Gold Fields mine east of Johannesburg, reported by police and Neal Froneman, the CEO of Gold One International, was the latest violence to hit South Africa's mines in months of unrest.

Company spokesman Sven Lunsche said some 12,000 of the company's workers "continue to engage in an unlawful and unprotected strike" that began Wednesday. He said it involved an internal dispute between local union leaders and members of the National Union of Mineworkers, the country's largest union.

After apartheid ended in 1994, South Africa pressed to share the country's vast mineral wealth with its impoverished black majority. But the hoped-for result has not occurred. A small black elite has become billionaires off mining while most South Africans continue to struggle against mounting unemployment, deeper poverty and a widening gap between rich and poor that makes the country one of the most unequal on Earth.

The mine where the violence took place Monday has previous business ties to relatives of Nelson Mandela and President Jacob Zuma — and was the site where firebrand politician Julius Malema, an avowed enemy of Zuma, pledged last week to make the nation's mines ungovernable.

South Africa's mining unrest reached a bloody climax on Aug. 16 when police shot 112 striking workers, killing 34 of them, at a platinum mine at Marikana, northwest of Johannesburg. The state violence was reminiscent of apartheid days and has seriously damaged the government's image.

Outrage at the police killings was exacerbated by prosecutors, who last week charged some 270 miners arrested at the scene with the murders and attempted murders of their striking co-workers — people who were killed by police. The National Prosecuting Authority was forced to retract Sunday, withdrawing the charges made under an apartheid-era law.

On Monday, 91 arrested miners were released, much to the joy of their ululating and singing family members and supporters. But there were tears for the many more who remained in custody.

The Independent Complaints Police Directorate has reported receiving complaints from more than 140 miners that they were beaten up in custody by officers trying to get them to name the strikers who hacked to death two policemen who were among 10 people killed in violence that led up to the shootings.

The directorate also is investigating police officers on 34 murder charges and 78 attempted murder charges in the shootings, although no officers have been suspended. A judicial inquiry is to report to the president by January.

Policy say they acted in self-defense. No officer was hurt during the Marikana shootings.

Also Monday, the Khulumani Support Group of some 80,000 survivors of human rights violations under apartheid said it filed an urgent appeal for a U.N. special rapporteur to assess what happened to the miners killed at Marikana, after reports that autopsies showed that many had been shot in the back.

In Monday's violence at Gold Fields, miners dismissed after a wildcat strike in June joined miners who lost their jobs two years ago to try to stop other workers and managers from reaching the mine.

Froneman said as police were called to disperse them, the protesting miners stoned a vehicle carrying people to work.

"Our security had to intervene, they used rubber bullets and police used rubber bullets and tear gas," Froneman told The Associated Press. "Four people were slightly wounded and all have been released from the hospital."

But police spokeswoman Pinky Tsinyane said one of those wounded was in critical condition. The different versions could not immediately be reconciled. Tsinyane also said four people were arrested for public violence.

The Gold Fields mine was bought two years ago by a group including Zuma's nephew and a grandson of anti-apartheid icon Mandela. The two allegedly never paid for the mine but stripped it of most assets and now are being sued by liquidators. They have also failed to honor court orders to pay tens of thousands of dollars to the miners who were thrown out of work.

Cabinet ministers, meanwhile, sought to reassure investors Monday even as news of the latest clash emerged.

"The tragic incident at Marikana is not a reflection of the business environment in South Africa," Collins Chabane, the minister of state in the presidency, told foreign reporters. "The government remains in control of the situation and law and order continues to prevail. The country continues to fully support direct investment and appropriate incentives and the legislative framework is in place to give confidence and predictability to investment decisions."

Legislator James Lorimer of the opposition Democratic Alliance blamed the latest violence on Malema, an expelled youth leader of the ruling African National Congress who has been using the unrest to try to oust Zuma from power.

Malema, who has called for the nationalization of South Africa's mines and for Zuma to resign over the police killings, went to the gold mine last week and told miners they must fight for their economic freedom.

He sent a message on Twitter on Monday saying he was addressing striking workers at the Gold Fields mine. "(The) Mining Revolution goes on and on and on," he wrote.

The violence that led to the police shootings at London-registered Lonmin PLC mine at Marikana and the Gold One International gold mine was at least partially rooted in union rivalry. Upstart unions have stolen thousands of members away from the dominant National Union of Mineworkers.

Negotiations continued Monday between Lonmin managers, unions and the Department of Labor to resolve workers' demands for a minimum monthly wage of R12,500 ($1,650).

Lonmin said only 4.5 percent of workers reported for work Monday. The strike that began Aug. 10 is crippling the company, which has said it probably cannot meet debt obligations due at the end of September.

Like the ANC, the politically connected National Union of Mineworkers is accused by rank-and-file workers of cozying up to management, of being more concerned with business than with workers' needs and with losing focus by spearheading Zuma's bid for re-election as ANC president next December.

The general secretary of the powerful Congress of South African Trade Unions vowed Monday to speak out.

"What I will not do is agree to be blackmailed and to keep quiet when things are going so wrong in society," Zwelinzima Vavi, who heads a faction that wants Zuma out, told shop stewards in Johannesburg.