Iran said on Sunday the UN nuclear watchdog had closed two major issues relating to the scope of its nuclear programme, which the West suspects is aimed at acquiring atomic bombs.
Tehran agreed with the International Atomic Energy Agency in August to answer outstanding questions by December about its atomic work, which it insists is purely for civilian purposes.
"We have received two formal letters ... from the IAEA informing us that the case of P-1 and P-2 (centrifuges) and also the case of uranium metal are closed," Foreign Ministry spokesman Mohammad Ali Hosseini said.
There was no immediate official IAEA comment. A November 15 IAEA report said Iran had provided "consistent" answers clarifying past centrifuge development work, although the answers were still being checked for completeness.
It said Iran had also turned over a nuclear black-market document describing how to mould uranium metal into spheres for atom bombs. The IAEA was consulting with Pakistan, the apparent provenance of the document, for more information.
The report did not say either issue was "closed", but that the IAEA was moving on to focus on other outstanding questions on a list it hopes Iran will answer by the end of the year.
"Our letters would not differ from the words in the board report, but Iran may use their own wording in their statements," said one senior UN official familiar with Iran-IAEA contacts.
Iran uses a 1970s vintage centrifuge, called the P-1, prone to breakdown but is researching an advanced P-2 model, which could enrich uranium faster. Enrichment can yield either fuel for nuclear power plants, Iran's stated goal, or for warheads.
IAEA Director Mohamed ElBaradei, summarising his report on Iran to the agency's 35-nation governing board, said on Thursday Iran was now making "good progress" towards resolving long outstanding questions by the end of this year.
Suspicions over Iran's atomic work has led to two sets of UN sanctions against Tehran. A third one has been mooted.
Hosseini said the next round of talks between Iran and the IAEA to settle remaining issues would be held on December 11.
NO SLOWDOWN:
Iran's top nuclear official Gholamreza Aghazadeh earlier said the talks would address questions about particles of arms-grade enriched uranium found by IAEA inspectors at Tehran's Technical University.
The other key outstanding issue is intelligence pointing to links in Iran between uranium processing, explosives tests and a missile warhead design. Iran has repeatedly denied this although has now agreed to examine evidence the IAEA has.
ElBaradei said the IAEA's knowledge of the scope of Iran's current atomic activity was diminishing as it was blocking inspector access to centrifuge development sites.
Iran has barred inspections beyond uranium production sites since its case was referred to the UN Security Council in February 2006. But the IAEA sees such access, provided for under its Additional Protocol with member states, as key to verifying there is no covert parallel military nuclear programme.
Aghazadeh was quoted by official news agency IRNA on Saturday as saying "it is too early to talk about implementing the protocol". He also ruled out a slowdown in enrichment work.
ElBaradei's report said Iran had installed 18 cascades of 164-machines in its Natanz facility, which analysts say lays a basis for producing significant amounts of nuclear fuel.
Western powers say Tehran has not done enough to win trust in its programme and want a tougher UN sanctions resolution. Iran's chief nuclear negotiator and the EU's foreign policy chief will meet on November 30 in London. The outcome of that meeting could help determine whether Iran faces new sanctions.