Mining giant Anglo American said its production of platinum dropped 29 percent in the fourth quarter of 2012 because of violent strike action at mines in South Africa.
"Equivalent refined platinum production decreased by 29 percent owing to the illegal strike action at the Rustenburg, Amandelbult and Union mines," the company said in a statement to the London Stock Exchange.
"The illegal strike took place between 18 September and 15 November 2012. This resulted in a loss of platinum production of 272,590 ounces during the quarter."
Anglo added that platinum production had slid to 416,000 ounces in the three months to December 31 compared with 583,000 in the final quarter of 2011.
Earlier this month Anglo American, the world's biggest producer of platinum, announced plans to axe 14,000 jobs in a dramatic restructuring of its strike-hit South African operations.
Months after being swept up in a deadly South African mining strike, Anglo's platinum subsidiary Amplats said it planned to close four shafts and sell a mine considered unsustainable.
The vast majority of job cuts, 13,000 in all, would be lost around Rustenburg, a city 110 kilometres (70 miles) northwest of Johannesburg that was the crucible of labour unrest that shocked the world last August and September.
Then, mineworkers' demands for higher wages crippled production across South Africa's mining sector and resulted in violence that claimed at least 50 lives amid a police crackdown.