South Africa's biggest union has staged a one-day strike to protest safety and security problems that have contributed to an increase in mining deaths this year.  Correspondent Scott Bobb reports from Johannesburg the work stoppage disrupted South Africa's largest industry and rattled commodity markets.

Thousands of miners marched to the Chamber of Mines in downtown Johannesburg to protest deadly accidents in South Africa's mines.  More than 200 workers have died this year.

The spokesman for the National Union of Mineworkers, Lesiba Seshoka, said the miners have asked mine operators to invest more heavily in safety, but the reforms have not been implemented.

"We are simply sending a strong message to them to say we are giving you a warning, to say if this kind of behavior continues you will see the real wrath of the mine workers of this country in a year or in a few months' time," said Seshoka.

The 250,000-member National Union of Mineworkers is South Africa's largest trade union.  It is protesting the resurgence of mine-related deaths that had declined from about 500 a year, 10 years ago.

Last October more than 3,000 miners were trapped for more than 24 hours after an elevator broke down.  All were rescued unharmed.

The executive director of South Africa's Chamber of Mines, Frans Barker, told national radio that mine operators are also concerned about safety.

"Unfortunately in the last year or so, our [safety] situation has deteriorated," he said.  "So we ourselves are concerned about that and we have ourselves launched initiatives and we also now want to sit down with the unions and to see what we can do."

He said operators want to include government officials in their meetings with the unions in order to address a shortage of mine inspectors.

Most of South Africa's mining accidents have been caused by rock falls or explosions, but critics charge that some are due to lax safety practices.

The miners say owners are more interested in maintaining production than high safety standards.

About 700 mines operate in South Africa.  They employ nearly 500,000 workers and provide 16 percent of gross domestic product.  South Africa is the world's largest producer of platinum, gold, and vanadium as well as a key producer of coal, diamonds, nickel, and uranium.

News of the strike drove up the price of platinum, while share prices for major mining companies fell on world markets.