"The IAEA will receive the report tomorrow," Iran's IAEA representative Ali Akbar told AFP late Wednesday. "It is a complete report concerning the questions posed by the agency and the history of Iran's nuclear activities," he added.
Earlier a spokesman at the IAEA's headquarters in Vienna told AFP; "The expectation is we will get it at midnight (2030 GMT Wednesday) at the airport in Tehran".
He said the declaration, which is expected to be a sheaf of documents, would be given to an IAEA inspector, who would then fly to Vienna.
Iran had promised Tuesday to provide the information following talks in Tehran with the foreign ministers of Britain, France and Germany.
Yielding to international demands for it to prove it is not developing nuclear weapons, Iran also agreed to allow tougher inspections of its nuclear sites and to halt uranium enrichment.
IAEA chief Mohamed ElBaradei said Tuesday in a statement he "hopes and expects that in the next few days Iran will deliver to the IAEA (International Atomic Energy Agency) a complete declaration of all its past nuclear activities."
ElBaradei visited Tehran last week to press for Iran's cooperation ahead of a October 31 deadline set by the agency for the Islamic republic to prove it is not secretly trying to develop nuclear weapons.
Iran has been asked to give records of what it has purchased and from where, how it tested and did development of centrifuges that can be used to enrich uranium and a history of its scientific experiments and development.
Officials said the Islamic republic has received assurances from the IAEA that such documents will remain confidential.
Non-compliance by Iran with the IAEA deadline could lead the nuclear watchdog to take the issue to the UN Security Council, which could then impose punishing sanctions on Tehran.