Johannesburg-listed shares of global mining company BHP Billiton drop more than 2 percent, while local firm Kumba Iron Ore also declines, after iron prices are squeezed by weaker demand from China.
Investors are concerned that a recovery in steel demand from the world's second-largest economy could stall, putting more pressure on the price of iron ore, which is used to make steel.
Billiton, which derived nearly a third of its 2012 revenue from iron ore, is down 2.4 percent at 291.28 rand.
Shares of Kumba are down 1 percent at 590.21 rand. - Reuters