Brazil's top appeals court has approved a request from prosecutors to open an investigation into the former and current governor of Rio de Janeiro state in connection to a kickback scheme at state-run oil company Petrobras.

A court statement released Thursday says it approved the investigation into Rio Gov. Luiz Pezao and former Gov. Sergio Cabral. Also to be investigated is Gov. Tiao Viana of Acre state.

Last week, prosecutors were given approval to investigate dozens of federal congressmen and some former top executive branch officials in connection to the Petrobras case.

Prosecutors say they've uncovered the biggest corruption scheme ever discovered in Brazil. The case involves at least $800 million in bribes and other funds allegedly paid by top construction and engineering firms in return for inflated Petrobras contracts.