The federal audit court said the decision was based on "evidence of fraud" in the tender process for the US$6bn Angra 3 nuclear power project in Rio de Janeiro.
Brazil's state-run oil company said it would pump an additional US$600mn into exploration and production projects over the next five years after posting a fourth quarter profit.
The state refiner says a bill to hold a referendum lacks technical and legal foundation.
The Argentine government and the International Energy Agency are to strengthen ties as the South American country prepares to assume the G20 presidency in 2018.
Brazil's national development bank says builders involved in the graft probe can access financing provided certain conditions are met.
A Sinopec-led consortium has reportedly agreed to financial terms, which include assuming an US$11mn debt owed to suppliers.
Authorities amend rules of the first three auctions of the country's second oil and gas licensing round.