Some 3,000 workers at a South African platinum mine owned jointly by African Rainbow Minerals (ARM) (ARIJ.J: Quote) and Anglo Platinum (Angloplat) (AMSJ.J: Quote), boycotted work on Thursday to protest over a colleague's death.

Work stopped at the Modikwa mine north of Johannesburg, which produced 294,721 platinum group metal ounces in fiscal year 2008, ARM said on its website.

Mining companies have suffered production losses after fatalities due to routine shutdowns ordered by the government for investigations, and work stoppages by union members who have vowed to stop work for a day to mark the death of colleagues.

Monique Swartz, head of investor relations at ARM which jointly manages Modikwa with Angloplat, the world's top producer of the metal, said the worker collapsed and died in the changing rooms on Wednesday night after completing his shift, and the company was treating the death as a non-mining related fatality.

We are not treating this as a mine-related accident or fatality, he died of natural causes and we are conducting an autopsy to verify the actual cause, Swartz said.

Labour has declared a day of mourning on the operation despite this not being a mine accident. (There is) no production for today, she said.

Lesiba Seshoka, the spokesman for the National Union of Mineworkers said the workers' stay-away would last for one day.

(Reporting by James Macharia)

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