Security forces Tuesday patrolled a platinum mine run by leading producer Lonmin in South Africa, where nine people, including two police, were killed in clashes between rival unions.
Scores of police patrolled the mine while a helicopter circled over the complex northwest of Johannesburg, as a military truck was seen driving inside.
Seven Lonmin employees were killed, while two of the police sent to quell the unrest were hacked to death in two days of violence which started off as a work stoppage on Friday called by one of the unions.
Police shot dead three protesters, saying they acted in self-defence.
In a statement Tuesday, Lonmin described the "serious and ongoing outbreak of violence" as a dispute between rival unions.
Police spokesman Dennis Adriao said "various police units were deployed" at the Marikana mine near Rustenburg in the North West province, about 100 kilometres (60 miles) from Johannesburg.
Television station eNews reported that a military truck drove into the complex Tuesday morning.
Workers failed to report for work as tension remained high, according to company and union officials.
"There is no work going on. The situation is very tense. Nine people have died in our property. If people don't feel safe they won't go to work," Tanya Chakanza, head of Lonmin investor relations, told AFP.
She would not immediately give statistics, saying only that "production has been severely disrupted" since the illegal strike on Friday by thousands of rock drill operators.
Lonmin shares fell 4.45 percent on the London Stock Exchange.
Of the workers killed, two were security guards who were stabbed and had fire bombs hurled at their car. One miner was shot while trying to report for work Sunday night, while another was hacked to death in his hostel room.
Strikes and riots have hit the country's platinum mines -- including Aquarius and Impala -- in recent months, but the violence at Lonmin was among the worst seen in recent years.
South Africa's police chief Riah Phiyega and provincial police officials met with the mine's management until the early morning hours Tuesday to discuss a plan to avert further violence, Adriao said.
Violent clashes broke out Sunday at the mine run by Lonmin, the world's third largest platinum producer, in a battle for dominance between the leading National Union of Mineworkers (NUM) and the smaller Association of Mineworkers and Construction Union (AMCU).
The AMCU broke away from NUM and is reportedly trying to recruit members on promises of bargaining improbably huge pay increases.
The recruitment drive has been seen as bordering on intimidation by some. AMCU officials were not readily available for comment.
Deadly clashes at South African mines have happened in the past during strikes over wages, when workers belonging to rival unions do not heed the strike call.
In February two workers were killed at a mine owned by Impala Platinum during a lengthy strike that shut down operations.
The mining sector is the biggest private employer in South Africa, whose workforce is among the world's most unionised.