Mitsui reached an agreement to purchase all of the firm's common shares held by state development bank BNDES and by Brazilian asset manager Opportunity, totaling 15.88 million shares.

The deal value was not disclosed by the company.

Based on Thursday's closing price of Ouro Fino shares, the stake bought by Mitsui is worth around 344.6 million reais ($66.09 million).

The deal is subject to the approval of antitrust authorities, Ouro Fino said in a securities filing.

($1 = 5.2141 reais)

(Reporting by Peter Frontini; Editing by Steven Grattan)