Angola said it has offered to buy Anglo American’s majority stake in De Beers, facing off against other potential suitors including neighboring Botswana.

State-owned Angolan gem producer Endiama presented “a concrete and well-defined proposal” to Anglo and is now moving ahead with “subsequent actions,” CEO José Manuel Ganga Júnior said in an interview in the Angolan capital, Luanda. He declined to provide further details, saying the talks are confidential.

Anglo American declined to comment.

London-listed Anglo is looking to divest its 85% stake in the iconic diamond miner as part of a restructuring process that began 17 months ago, with investor groups led by former De Beers executives Gareth Penny and Bruce Cleaver throwing their hats in the ring as the formal sales process got underway in June.

Botswana — where De Beers mines most of its gems — is also seeking to boost its 15% stake to a controlling share, with President Duma Boko calling the effort a “matter of economic sovereignty.”

Endiama’s offer signals a shift in Angola’s own ambitions, after the nation’s mines ministry said in September it was seeking to take a “strategic” minority stake in De Beers, with the objective of fostering a partnership with Botswana.

Angola is Africa’s leading diamond producer by value, with output last year surpassing Botswana’s production for the first time in two decades, according to the latest report by the Kimberly Process, an international certification program. De Beers has an exploration joint venture with Endiama.

Endiama expects Angola to “reach an understanding” with Botswana, Ganga Júnior said, declining to say whether discussions have taken place. While Angola is bidding for Anglo’s full stake in De Beers, the final outcome is uncertain.

De Beers is “such a large business that we believe there is room for several partners,” he said. Botswana, as an existing De Beers shareholder, has the right to match any offers from outside parties.

The Angolan company is seeking to tap De Beers’ proprietary mining technology, along with its marketing system, Ganga Júnior said.

“These are factors that, if we’re part of De Beers, will automatically allow us to take bigger leaps forward,” he said.

Botswana’s minerals and energy minister, Bogolo Kenewendo, didn’t immediately respond to a request for comment sent by text message.