Protesting South African miners have blocked access to shafts of platinum company Amplats as officials sought to prevent the widening strike movement from turning into a nationwide revolt.
The latest unrest broke out on Wednesday along roads leading to a shaft run by Amplats - the world's top platinum producer - in the same region as the Lonmin plant where 45 people have died in a wildcat strike that started last month.
Al Jazeera's Tania Page, reporting from Marikana in North West province, said that workers are demanding a pay raise to 12,500 rand, or about $1,500.
"Its unclear at this stage where the peace negotiations are at, since they stalled for several days."
She said that protests in Marikana, 100km north of Johannesburg, were inspiring protests to spread further. On Tuesday night, at the world's largest platinum producer, Amplats, about a thousand workers confronted security.
"The company warned its workers to not turn up for work today because of high levels of intimidation," she said.
Workers "were unable to clock in for night shift due to fear of intimidation and threats by unidentified individuals in and around our Rustenburg operations", Amplats spokesman Mpumi Sithole said in a statement.
Workers at Gold Fields' Beatrix gold mine, close to Johannesburg, were also due to join the strike later this week, the National Union of Mineworkers (NUM) said on Wednesday.
"At Impala Platinum, workers are demanding a further 10 per cent increase after they received a similar increase about a month ago," our correspondent said.
At least 45 people have died - including 34 in a police shooting last month which has been described as the worst case of police violence since the end of apartheid - since a strike over pay was launched at the Marikana mine.
The site is run by Lonmin, the world's third biggest platinum producer, and workers there have yet to reach a deal with management and return to work.
Amplats said it had halted work at its four Rustenburg mines, which account for 17 per cent of its output, due to fears for the safety of its 19,000 staff there.
Mines under pressure
Amplats's Rustenburg shafts have been under pressure since platinum prices collapsed after the 2008 financial crisis.
Analysts expect them to be targeted as "restructuring candidates" by parent company Anglo American.
Tensions have been high at the mine, where workers refuse to return to work since striking on August 10 unless the world's number three platinum producer bows to demands for a wage increase to $1,526.
The company said only three per cent of its 28,000-strong workforce resumed work, and strongly condemned the intimidation of non-strikers.
"The continuing efforts of a minority to keep the mine closed through threats of violence now pose a real and significant threat to jobs," it said.
Wage talks between the management and workers in Marikana, meanwhile, are in danger of breaking down, religion-based mediation group Bench Marks Foundation said.
An estimated 8,000 striking miners and their followers, shadowed by police in armoured cars and helicopters, marched on Tuesday to a hospital to see some of the 190 miners who say they were beaten and tortured in police custody.
Malema took up the workers' call, urging employees at Gold Fields to strike for five days every month until their demands were met.
"This is a serious revolution, don't give up!" Malema told a cheering crowd of around 3,000 at a stadium in Carletonville, west of Johannesburg. "You must render the mines ungovernable."
He accused the NUM of being aligned with the country's political elite.
"There must be a national strike. They have been stealing this gold from you. Now it is your turn. You want your piece of gold. These people are making billions from these mines," Malema said.
Malema was expelled earlier this year by the ruling ANC party for ill-discpline. He has since been a vocal critic of President Jacob Zuma, who belongs to the ANC.
Once a staunch supporter of Zuma before a fallout as the party's youth leader, Malema has stated he wants to see the head of state removed from the ANC leadership at forthcoming party elections in December.
The winner of the vote will automatically become the ANC candidate for the 2014 presidential elections and likely be South Africa's next president.