South African miners trapped in Doornkop Gold Mine fire

Doornkop Gold Mine overlooks Johannesburg's Soweto township

Rescue workers in South Africa are trying to free nine miners still trapped underground after a fire at Doornkop mine west of Johannesburg.

Eight other miners have successfully been brought to the surface, the mine owners Harmony Gold said.

"Efforts continue to establish the whereabouts of a further nine employees who are currently unaccounted for," spokesman James Duncan told the BBC.

The fire began on Tuesday evening about 1,700m (5,600ft) below ground.

Mr Duncan said rescue teams were struggling to access the affected area because of smoke and rock fall.

Mining is vital for South Africa's economy

There is some confusion about how exactly the fire began.

Harmony Gold has confirmed there was some seismic activity in the area.

South Africa's National Union of Mineworkers says this resulted in the collapse of underground rocks which caused the fire.

"It... caused damage to ventilation pipes, electric cables and water pipes. The damage to electric cables triggered fire underground which is still burning," the NUM said in a statement.

The eight workers who were successfully rescued on Wednesday had managed to reach a "refuge bay", where there was compressed air and water kept for such incidents.

The BBC's Andrew Harding in Johannesburg says the nine missing mine workers will be carrying their own packs of oxygen and Harmony Gold hopes they will have made their way to other refuge bays underground.

Our correspondent says the Doornkop mine is just outside the city, on the west rand - a rich but deep seam of gold.

In recent years the majority of deaths underground have occurred in illegal mines, he says.

The Harmony Gold team has left the "Mining Indaba", Africa's largest annual mining conference, being held in Cape Town.

The meeting has been overshadowed by a major strike which is currently crippling South Africa's platinum production.

The mining industry is a vital part of the South African economy.

Mark Lowen goes inside a South African gold mine