"Remember, it's willing buyer, willing seller. There's no expropriation," Tsvangirai told a conference on Zimbabwe's political and economic prospects in neighbouring South Africa's commercial capital.

Foreigners regularly cite the law as their main concern about investing in Zimbabwe, which is desperate for external capital to rebuild the economy after a decade of chronic mismanagement and decline under President Robert Mugabe.

Zimbabwean President Mugabe told Reuters in an exclusive interview earlier this month, that he will press ahead with plans to transfer control of foreign firms - including mines and banks - to local blacks.

"What's being implemented are minimum thresholds. You can't start with 51%," Tsvangirai said. "But you also have to say how, over time, you are going achieve the maximum threshold."

In the more immediate future, companies would have to adopt much lower levels of black ownership while presenting a road map towards ultimate black Zimbabwean majority ownership, he said.

Tsvangirai, whose Movement for Democratic Change (MDC) party is now in a power-sharing administration with arch-rival Mugabe's Zanu-PF, said that the government was still drawing up the thresholds for the minimum, initial levels of black ownership.

As a hypothetical example, he spoke of a minimum initial black ownership level of 10% for the country's key mining sector.