The Brazilian state-run oil producer, Petrobras, has delayed by two months one of the world's largest planned share offerings.
The firm said Brazil's energy regulator would not have an independent estimate of the value of oil, the crucial next step in the process, until late August.
The deal is valued at 150bn reais ($86bn; £58bn).
It would see the government receive shares in return for giving Petrobras access to up to 5bn barrels of oil.
Just hours earlier, the deal had received shareholder approval.
The company said it now hoped to carry out the public share offer in September.
Separately, Petrobras predicted that Brazil would become more strict with regards to deepwater offshore drilling projects off its coast.
Petrobras has ambitious plans in the region.