Botswana, the world's second-largest diamond producer, will require companies to sell a 24% stake to locals under a revised law awaiting presidential approval, part of a broader African push for greater mining control that lawyers expect to trigger legal disputes and compliance issues.

Botswana's parliament passed amendments to its mining law in July, a month before the country announced the discovery of a 2,492-carat rough stone, the second-largest diamond ever found.