Iran has committed to a timetable for co-operation with the International Atomic Energy Agency in its investigation into Tehran's nuclear activities.
Iran's mission to the IAEA said in the memorandum that it had cleared up questions from the UN's nuclear watchdog about its experiments with plutonium.
The plutonium issue is one of several over which the UN Security Council has imposed sanctions to get Iran to co-operate with the IAEA, which is investigating US charges that Iran is covertly developing nuclear weapons.
The text published on the IAEA's website at the request of Iran's mission, said: "On 20 August 2007, the agency stated that earlier statements made by Iran [on the issue of plutonium] are consistent with the agency's findings and thus this matter is resolved."
It said the IAEA would be communicating this "officially … to Iran through a letter".
There was no official comment from the IAEA, but a UN official said the document reflected both the IAEA's and Iran's views and that the question of whether Iran had experimented with plutonium more recently than it had stated and that there was plutonium unaccounted for, had been resolved.
Scepticism
Another diplomat familiar with the agreement, however, suggested that while the document was encouraging in reflecting agreement between Tehran and the agency on the focus of outstanding questions, its language was loose enough to allow Iran loopholes, should it not decide to fully honour its commitments.
The US says Iran is playing at co-operating with the IAEA to avoid further UN sanctions and that it is still defying the UN demand for it to stop making enriched uranium.
Plutonium and enriched uranium are both parts of civilian nuclear programmes but can also be used to make bombs.
The timetable said Iran has already agreed to five new IAEA inspectors and is opening the door to resolving concern over documents that allegedly point to it having a secret military project for developing a bomb.
Other issues are Iran's work on sophisticated centrifuges to enrich uranium and its building a heavy-water reactor to make plutonium.
Iran also said it would answer questions about an alleged "Green Salt project" which US intelligence says involves a secret site to prepare uranium, and also alleged research on putting nuclear warheads on missiles.
Despite its promised co-operation, however, Tehran said in the text that these were "politically motivated and baseless allegations".