A judge in Rio de Janeiro convicted a former executive of Brazil's state-run oil firm Petrobras of fraud on a contract awarded to conglomerate Odebrecht SA and sentenced him to a maximum four years in jail on Jan. 12.

Prosecutors said Jorge Zelada, former head of Petrobras' international division, helped scrap a competitive bidding process, resulting in Odebrecht winning a contract to analyze Petrobras' potential environmental liabilities abroad in 2010.

Zelada faces additional charges including corruption and money laundering in the southern city of Curitiba, the epicenter of Brazil's largest-ever corruption investigation.

Zelada's lawyer Ricardo de Moraes was not immediately available for comment but told Globo News he planned to appeal.

Prosecutors are unraveling a scheme they say involved engineering companies overcharging Petroleo Brasileiro SA, as the company is formally known, and used the excess funds to bribe executives and politicians.