South African police fired rubber bullets at protesters Wednesday at platinum giant Anglo American which ordered workers to end an illegal strike a day after a wage deal was brokered at nearby Lonmin.
The fresh violence in northwestern Rustenburg raised fears that a wage deal at Lonmin -- where 45 people died in nearly six weeks of unrest -- had set a dangerous precedent for wage negotiations amid a flare of copycat protests.
"Anglo American Platinum has communicated to its employees the requirement to return to work by the night shift on Thursday 20 September, failing which legal avenues will be pursued," the firm said in a statement.
The ultimatum by the world's top platinum producer came after police arrested 22 people in protests after it had urged workers to return to five mines that were shut down over safety fears last week.
"They refused to disperse. Police had to revert to tear gas and stun grenades and there was also rubber bullets fired," police spokesman Dennis Adriao told AFP, about an illegal gathering of around 500 people at an informal settlement.
"They were throwing stones and trying to destroy property," he added.
Hours after the fresh clashes, Amplats declared that an illegal strike was underway that violated a court order obtained last week after having called on staff to return to work no later than Wednesday.
"Anglo American Platinum urged its employees to return to work by no later than today," said the company which employs 26,000 people in Rustenburg.
"Given the authorities' assessment that it is safe to go to work, the company is now left with no alternative but to declare those who have not returned to work to be participating in illegal industrial action."
The company did not specify what legal action it could take, but legislation governing unprotected strikes in South Africa gives employers dismissal rights.
The unrest came shortly after workers at the nearby Lonmin-owned Marikana mine agreed to return underground, after sealing a pay hike deal late Tuesday following more than three weeks of talks.
The paralysed British firm became the epicentre of spiralling tensions in the mining region after police gunned down 34 protesters last month which sent shockwaves around the world with its echoes of apartheid brutality.
The workers' wage demands and threats of deeper strike action were taken up by other gold and platinum miners, raising fears of a major economic fall-out as the rising tensions forced several shaft closures over safety fears.
Under the deal, Lonmin miners will return to work at 7:00 am (0500 GMT) Thursday in return for raises that fell short of demands for 12,500 rands (1,160 euros, $1,520) but ranged between 11-22 percent, plus bonuses.
Shares in Lonmin, the world's third-biggest platinum producer rallied in London on Wednesday morning after the breakthrough, with stock slumping by almost 30 percent since the start of the year.
At about 0725 GMT, Lonmin shares surged 8.99 percent to 708.4 pence on London's second-tier FTSE 250 index.
But warnings were also sounded after workers won gains from the crippled firm by militantly bypassing the country's mining union giant the National Union of Mineworkers (NUM).
"The normal bargaining processes have been compromised. It does suggest that unprotected action, an element of anarchy, can be easily rewarded," Frans Baleni, the NUM general secretary, told Talk Radio 702's Eyewitness News.
Analyst Iraj Abedian, CEO of Pan African Investments, said the Marikana crisis and its resolution marked a watershed.
"There is no question that a precedent is set for workers to go on wildcat strikes and in a way try their best to negotiate a different term than what they had agreed to," he told AFP.
As the strikes dragged on, a semblance of stability saw several mines reopen after the government announced a security clampdown with police acting swiftly to stamp out illegal gatherings and confiscate machetes and other weapons.
The government has defended its crackdown, with the key mining industry forming the backbone of the continent's powerhouse.
Mining directly employs around 500,000 people and, if related activities are factored in, accounts for nearly one-fifth of gross domestic product and twice as many jobs.