SAO PAULO, April 10 (Reuters) - Japanese conglomerate Mitsui & Co has agreed to form a joint venture with Brazilian energy company Geo to build and operate plants of sugar-cane based biogas and biomethane in the South American country, it said in a statement on Wednesday.

Mitsui & Co, which is partnering with Geo through its Brazilian unit Mitsui Gas, did not disclose how much it would invest in the joint venture. (Reporting by Leticia Fucuchima; writing by Andre Romani; editing by Gabriel Araujo)