Indonesia has passed a ban on exports of raw minerals after making last-minute concessions for the two biggest US mining operations there.
Freeport-McMoRan and Newmont will temporarily be exempt from the ban, which took effect on Sunday.
The ban is aimed at boosting domestic mineral processing to keep a greater share of mining profits in Indonesia.
Critics claim it will lead to mass-layoffs and worsen a widening trade deficit. The Indonesian Chamber of Commerce and Industry has warned as many as 800,000 jobs might be at risk.
Revised legislation giving effect to the ban was given President Susilo Bambang Yudhoyono on Sunday for signing. it was introduced in 2009.
Metal prices, nickel in particular, rose sharply on Monday on speculation the ban may cause a supply squeeze.
