Big mining companies slammed the Mineral and Petroleum Resources Development Bill during its preparation, calling it "creeping nationalisation" and saying it would undermine international investor confidence in South African industry.

Mineral and Energy Minister Phumzile Mlambo-Ngcuka said this week she would ask President Thabo Mbeki to test industry and opposition allegations that it violates the constitution before signing it into law.

Black investors have welcomed the new law, saying it will open the industry to the majority barred from economic participation under white apartheid rule, which ended in 1994.

"The bill is a victory for South Africa. It's a victory for everybody," said Patrice Motsepe, executive chairman of black-owned African Rainbow Minerals, after watching the initial vote this week.

The bill was adopted by the National Council of Provinces, equivalent to a senate, yesterday and returned to the National Assembly for a final vote, including a technical amendment made yesterday morning that removes a five-year deadline for expropriation claims.

But the National Union of Mineworkers (NUM) said it did not go far enough to break the white domination of the industry that has made South Africa the richest country in sub-Saharan Africa.

NUM general-secretary Gwede Mantashe told Reuters in an interview yesterday the bill should have set targets for the inclusion of blacks in the management of existing mining firms.

"We have a handful of mine managers who are black. The process is very slow and it must be accelerated," Mantashe said.

The Constitutional Court is on a mid-year recess until August and officials were unable to predict when the country's top judges would be able to examine the bill and pronounce on its validity.