"The agreement with Mubadala will make a significant contribution to Guinea's economy by enabling the expansion of CBG to more than 20 million metric tons of bauxite per year," Guinean Mines Minister Mohamed Lamine Fofana was quoted as saying by the Emirates News Agency.

The agency did not report the duration or value of the contract, which was concluded between CBG and the Emirates' investment fund Mubadala Development Co.

The Guinean company has an annual production of 13.5 million tonnes.

Fofana was also quoted as saying at a signing ceremony in Abu Dhabi that the new agreement would add $500 million to Guinea's gross domestic product.

In March Fofana said Guinea had started negotiations for Mubadala to take a stake in CBG, a joint venture between Guinea, Alcoa and Rio Tinto.

Guinea is the world's largest exporter of bauxite. The UAE's Dubai Aluminium Co (Dubal) produces around 1 million tonnes a year of aluminium, according to Gulf business website zawya.com.