Rio Tinto PLC's (RTP) diamond operations in Zimbabwe are threatened by legislation that would force the company to hand over majority ownership to local groups, the company's chief executive for diamonds and minerals said Tuesday.

"The indigenization legislation we believe is unworkable, and we are hopeful the government of national unity will not enforce it," Harry Kenyon-Slaney told Dow Jones Newswires.

Rio Tinto owns and operates the Murowa diamond mine in Zimbabwe. Zimbabwe's Indigenization and Economic Empowerment Act requires businesses in Zimbabwe to sell majority stakes to black owners.

The Anglo-Australian miner would support a process similar to South Africa's Black Economic Empowerment program, which requires miners to had over ownership stakes in assets to historically disadvantaged South Africans, Kenyon-Slaney said.

Kenyon-Slaney said he was encouraged by the Zimbabwe government of national unity's recent efforts to consult with the mining industry before implementing the indigenization legislation.