An Omani state-backed fund has acquired shares in Angola’s Catoca diamond-mining joint venture from Russia’s Alrosa PJSC.

Maaden International Investment LLC’s stake purchase was announced by Mineral Resources Minister Diamantino Azevedo on Thursday. Alrosa, which held a 41% interest in the Catoca operation, has been sanctioned by the US, EU and their allies.

Alrosa “will no longer be part of this partnership due to international sanctions imposed on Russia,” Azevedo said in the capital, Luanda. The restrictions were “affecting Angola’s credibility in the international diamond market,” he said.

While Alrosa is mainly active in Russia, it has been present in Angola since the early 1990s and helped develop Catoca – majority owned by the Angolan state – into one of the world’s largest diamond mines.

Azevedo had said earlier that the state-controlled Russian company had become a “toxic partner due to the global context.” Aysen Nikolayev, president of the Yakutia region in Russia, which owns a stake in Alrosa, said in September that the company was discussing the future of its Angolan projects and in talks with potential investors.

The Russian company vies with Anglo American Plc’s De Beers as the world’s largest producer of diamonds. Diamond prices are currently in a prolonged slump amid weak Chinese demand, too much supply and pressure from lab-grown gems.

Maaden International, which is owned by a consortium of Omani investors led by a state-owned firm, bought a 24% interest in a gold producer from Russian investors, including billionaire Alexander Nesis, in January.

Alrosa’s press service didn’t immediately respond to a request for comment.