JOHANNESBURG (AP) — Demands for higher wages spread to at least two other platinum mines in South Africa and raise fears instability could spread to more of the country’s mines that provide 75 percent of the world’s supply of the precious metal.

South Africa’s miningweb.co.za Web site calls it “a possibly ominous development.” A 12-day strike at the Lonmin PLC mine resulted in police killing 34 striking miners and wounding another 78 last week.

Spokeswoman Kea Kalebe of Royal Bafokeng confirmed about 400 people are protesting Wednesday outside the company’s Rasimone platinum mine.

Demands being made by some workers at Rasimone and Anglo American Platinum’s Thembelani mine appear tied to rivalry between an upstart union and the veteran National Union of Mineworkers. They reflect charges NUM puts political interests before those of miners’.