Banking officials said the banks would in effect provide much of the money to pay the interest due them.
Banking officials said that only some countries in the Islamic world now bar the practice.
Brazil will continue to pay 30 percent of interest as it comes due, banking officials said.
International banking officials say the $900 million was not recorded in the country's published budget.
Federal banking officials say nothing so drastic is possible this time.
Second extensions are sometimes given, but not often, banking officials said.
But Swiss banking officials said that without an account number, they could not help her.
Banking officials point to recent reforms, like an increase in the amount of bank branches that foreign companies can set up.
"We're talking among ourselves, some banking officials, others here in town," he said.
That lack of regulatory oversight was a concern to American banking officials.