Diamonds are a key part of South Africa's economy

Deputy minister of minerals Lulu Xingwana questioned De Beer's commitment to black empowerment, saying she was disappointed with the choice.

De Beers is the world's largest diamond firm and already has come under fire for its lack of black executives.

Firms are being urged to promote and hire more black employees to redress damage done by the apartheid regime.

The government is implementing rules and legislation that are designed to spread ownership of South African firms to the black majority.

Sparkle

De Beers announced earlier that Gareth Penny would take over as managing director from Gary Ralfe next year.

Ms Xingwana told Parliament that the government wanted to "again express our exasperation and disappointment by De Beers' announcement that it will replace one white managing director with another white managing director".

"This is the same company whose board of directors is lily-white and male dominated."

Black workers are too far down the job ladder, the government says

De Beers has not commented on the remarks.

A number of companies have been involved in black empowerment deals recently, with finance group Old Mutual agreeing to hand over 13% of its local business to black investors and staff.

The Elephant consortium, a black investment group, announced plans to buy a 10.1% stake in the South Africa's biggest phone company, Telkom.

Legislation is also on the way to increase the number of blacks working in the tourist industry as well as raise the number of diamonds processed locally.

De Beers produces about 60% of the world's diamonds and has already come under fire from the government.

There have been calls for De Beers to shift its sales division from London to Africa, while President Thabo Mbeki criticised Anglo-American - which owns 45% of De Beers - for suggesting that investing in South Africa carried a political risk.