South African police fired rubber bullets at protesters and raided worker hostels at platinum giant Lonmin to seize weapons in a crackdown on unrest in the key mining industry Saturday.

The army has been deployed as back-up to the troubled Rustenburg platinum belt where militant protests have forced several mine closures since officers gunned down 34 people last month at the London-listed company's Marikana mine.

"The army has soldiers in Marikana deployed in request of the South African Police Service," Brigadier General Xolani Mabanga told AFP.

"We are there just to render support but the lead in the operation is the South African police."

Forces moved into Marikana less than 24 hours after the government announced a security clampdown on the unrest that has forced three leading producers to halt mines on the world's richest platinum deposits.

Soldiers were there to help with the police's cordon and search operation, said Mabanga. With no more than 150 military personnel on the ground they were not there to maintain law and order or for riot control, he added.

Five hundred officers, assisted by the army, raided hostels at Lonmin's mine at 2:00 am (0000 GMT) seizing piles of metal rods, machetes and sticks.

Later that morning, police fired tear gas to disperse gathering protesters, with clashes breaking out as workers regrouped and threw stones at officers amid the shacks opposite the mine.

It was the biggest show of force by police since August 16, when officers shot dead 34 miners.

Since then, police had monitored the subsequent spike in protests largely from a distance, as shockwaves from the shootings, with its echoes of apartheid-era brutality, spread across the world.

"Wherever we see this unruly behaviour and people taking the law into their hands by embarking on unprotected gatherings and illegal gatherings, we are definitely going to act," police spokesman Thulani Ngubane told AFP.

"The police are not going to hesitate to act. We are going to act as we have started acting and we are going to continue doing that."

Plumes of black smoke had poured into the sky from burning tyres which workers used as barricades along with large rocks dragged across the dirt roads inside the humble settlement. But the area was calm by the afternoon.

"We used rubber bullets, we used stun grenades," Ngubane confirmed, saying that in addition to seven arrests of protesters at a mine on Friday police had detained at least another 12 people.

An AFP photographer on the scene saw a man bleeding after having been shot in the arm and the side of his body, while television news channel eNCA showed a person with a bloody leg wound.

"A police nyala (armoured truck) drove past us, we were a group of women and others ran away. I just stood there watching and they shot me in my leg," Melita Ramasedi told the Sapa news agency, showing her bleeding leg.

Worker representative Molisi Phele said workers had gathered to get feedback after mediated talks.

"Really this is disturbing," he said. "Tomorrow they will say people are violent but they police started (it)."

The troubles at Lonmin, the world's third largest platinum miners, over a wage dispute in which 45 people have died, have spread to surrounding mines and to a Gold Fields mine near Johannesburg.

The world's top platinum producer Anglo American Platinum has closed five mines because of safety fears. Leading ferrochrome producer, Xstrata Alloys, and Aquarius Platinum halted work on Friday due to the mounting protests.

The police clampdown is targeting the illegal gatherings, weapons, incitement and threats of violence that have characterised the unrest surrounding the industrial dispute.

President Jacob Zuma's spokesman Mac Maharaj told AFP that the actions were "very proper, firm, some people would even say, inadequate measures" given the violence and threats of intimidation.

"It is necessary to act because this is a point at which we have to make certain important choices. If we allow the situation to continue, the economy will suffer severely and we will be going down the road of lawlessness."

Mining is the backbone of South Africa's economy. It directly employs around 500,000 people and once related activities are included accounts for nearly one-fifth of gross domestic product.