Heavily armed police forces backed by armored vehicles opened fire and deployed tear gas against striking workers at South Africa's Marikana platinum mine on Thursday, killing several people in the latest deadly clash there.

The Reuters news agency reported that police fired automatic weapons, killing at least a dozen people after a group of men sprang from behind a vehicle.

Meanwhile, a reporter for the AFP news agency said that several people were lying on the ground and bleeding from injuries after police fired tear gas and rubber bullets.

According to German news agency dpa, some reports said that the striking workers had shot first as the police advanced.

Some 3,000 members of the Association of Mineworkers and Construction Union (AMCU) have been striking for the past six days. Their demands remain unclear. The AMCU has made a push to expand its membership in the platinum mines, coming into conflict with the traditionally dominant National Union of Mineworkers (NUM).

At least 10 people have been killed since clashes broke out Friday of last week, including security guards and two police officers. Some were burned or hacked to death. The mine is located 100 km (60 miles) northwest of Johannesburg.

'D-Day'

Some 3,000 police began gathering at the mine on Wednesday, including camouflaged members of an elite riot control unit. Horses and helicopters were reportedly deployed.

"Today is unfortunately D-day," police spokesman Dennis Adriao said earlier on Thursday. "It is an illegal gathering. We've tried to negotiate and we'll try again but if that fails, we'll obviously have to go to a tactical phase."

But the leader of AMCU, Joseph Mathunjwa, had refused police demands and vowed the strike would continue.

"We're going nowhere," Mathunjwa shouted through loudspeaker to cheers from the crowd. "If need be, we're prepared to die here."

Mining operations disrupted

The unrest at the Marikana mine has forced the London-based company Lonmin to completely shutdown its South African operations, which account for 12 percent of global platinum output. South Africa is home to 80 percent of the world's known platinum reserves.

Lonmin has claimed to have lost some 15,000 ounces of platinum during the six days of disruption, saying that it is now unlikely to meet its production target this year of 750,000 ounces. The company's London listed shares dropped by 6 percent on Thursday, bringing its total losses to 13 percent.

slk/ipj (AFP, dpa, Reuters)