Workers at Russian aluminium giant Rusal's Guinea subsidiary Compagnie des Bauxites de Dian Dian (Cobad) went on strike on Thursday, a union leader told Reuters.
Rusal did not immediately reply to a request for comment, and it was not immediately clear whether production at the Cobad bauxite mine was continuing.
The workers at Cobad are demanding better working conditions and a salary increase, union leader Yamoussa Bangoura said by telephone, adding that Cobad was given notice of a strike on May 7.
"We have asked everyone to stop working until our demands are met," Bangoura said. Workers decided to strike after talks with Cobad management on Wednesday were inconclusive, he said.
Guinea is the world's second-largest producer of bauxite, an ore used to make aluminium, and a key supplier of bauxite to China. It produced 83-million tonnes of bauxite in 2021, Guinea's mines ministry statistics showed.
Cobad produced 3.59-million tonnes of bauxite last year, while Rusal's other Guinea operation, Compagnie des Bauxites de Kindia, produced 2.65-million tonnes, according to the mines ministry.
Cobad had stopped exporting bauxite from Guinea for nearly a month in March as Russia's invasion of Ukraine disrupted Rusal's supply chains.