Zimbabwe Chamber of Mines CEO Douglas Verden said that the industry body was still going through the bill, but that it "did not look very helpful to the mining industry".

"It would appear that there is a freebie of 25% in energy-supply materials miners and miners of precious metals and stones," he stated. "They call the 25% a noncontributory takeover by government."

The draft legislation also forced mining companies to be majority owned by locals.

"We're busy looking at it at the chamber at this minute and then we'll be deciding on what action we'll be taking," Verden said on the phone from Harare.

He added that the chamber would likely come up with a plan of action "in a few days". "Maybe we should take some different type of action, I'm not certain at this stage."

"It doesn't look very promising, but we'll have to wait and see," Verden concluded.

The world's biggest platinum-miner, Anglo Platinum, which has assets in Zimbabwe, was not immediately available for comment.

The next-biggest producer Impala Platinum reserved comment until it had time to go through the documents from Zimbabwe.

Rio Tinto, which had diamond interests in the country, declined to comment on the proposed legislative changes.

"We are studying the draft bill, but have no comment to make at this stage," spokesperson Nick Cobban said in reply to emailed questions.

Bermuda-registered platinum-miner Aquarius also had interests in the country, and had not immediately responded to emailed questions.