Brazil has announced it will begin enriching uranium officially, saying it has received the approval of the United Nations' nuclear watchdog.
Full production may not begin until summer of 2005
International Atomic Energy Agency inspectors paid a "successful" visit to the Resende enrichment plant in October, a minister told reporters.
Science and Technology Minister Eduardo Campos said production of enriched uranium would start within months.
However, an IAEA official told the BBC no final agreement had been reached.
The spokesman told the BBC the IAEA was still completing its assessment of Resende.
The BBC's Steve Kingstone reports from Sao Paulo that the agency is conscious of the need for consistency in its work at a time when it is also dealing with Iran on the same issue.
Privately, agency officials say a deal with Brazil is close and could be announced in the next fortnight but it seems that in its excitement the Brazilian government may have jumped the gun, our correspondent notes.
Mr Campos said on Wednesday that an IAEA team had visited Resende to verify information on work at the closely guarded plant.
"The visit was considered completely successful by both sides," he said.
"It means that from the point of view of international safeguards, the plant can start working."
He added that tests could start "immediately" though it could be eight months before production of fuel for nuclear reactors would begin.
The government had been refusing to show all of its centrifuge technology responsible for enrichment.
It had argued that its hardware was more advanced than that of other countries and must be protected from industrial espionage.
Brazil has two nuclear power reactors - Angra I and Angra II - and is considering constructing of a third.
There was speculation earlier in the week that visiting Russian President Vladimir Putin might offer some nuclear deal but nothing was announced.
However, Mr Putin did pledge help for Brazil's oil sector, its space programme and its bid for a seat on the UN Security Council.