In another development that seemed to show Iran edging towards compliance in revealing its program, International Atomic Energy Agency (IAEA) chief Mohamed ElBaradei said in Canada Thursday that a report Iran filed October 23 to answer the agency's questions was "comprehensive".
But he cautioned that the jury was still out on its accuracy.
In Tehran, meanwhile, a leading conservative opponent of Iran's acceptance of international demands for tough new safeguards fell into line.
Ayatollah Ahmad Janati, a key aide of supreme leader Ayatollah Ali Khamenei, told worshippers at weekly prayers Friday that the regime had acted with wisdom in accepting the demands of the IAEA before the UN watchdog's deadline ran out.
Despite these positive steps, Tehran still faces the possibility the IAEA will judge it to be in non-compliance with the nuclear Non-Proliferation Treaty (NPT) and send the issue to the UN Security Council, which could then impose sanctions.
A key question is whether traces of highly enriched uranium found by IAEA inspectors had come from an enrichment program that could make weapons-grade material or had come from contaminated equipment that had been imported, as Iran claims.
Nothing definitive is expected to happen Friday. The UN agency will now begin writing a report on Iranian compliance, with the matter to be considered at an IAEA board of governors meeting in Vienna on November 20.
The IAEA expects next week to receive a letter from Iran agreeing to allow wider and unannounced international inspections of its nuclear program, agency spokeswoman Melissa Fleming said at IAEA headquarters in Vienna.
"Our understanding is that we will be receiving the letter next week," Fleming said, without specifying the day. After this the IAEA would still have to fix a date for Iran to actually sign the protocol.
Iran agreed during an unprecedented joint visit by the British, French and German foreign ministers to Tehran on October 21 to sign up to the tougher inspections regime set out in an additional protocol to the international nuclear Non-Proliferation Treaty (NPT).
Iran's archfoe, the United States, has since expressed skepticism about the Islamic regime's readiness to deliver on its undertakings.
But ElBaradei said Iran's report "looks comprehensive."
He also told the German newspaper Frankfurter Allgemeine Zeitung Friday that IAEA inspectors were able to go where they wanted in Iran and were verifying the report.
In Tehran, Ali Akbar Salehi, Iran's ambassador to the IAEA, said Iran wanted there to be "no ambiguous points for the IAEA."
Iran admits in the report to failures in honoring nuclear safeguard commitments, Salehi had told AFP last week.
Salehi said the failures involved "some lab tests" but he said they were "not significant" and that "it is 100-percent clear that Iran has never been involved in anything that would indicate it was involved in a nuclear weapons program."
A Western diplomat said Iran "was already in non-compliance in September," when the IAEA set the deadline, giving Iran a last chance to come clean on its nuclear program.
He said some sort of non-compliance finding, even a "non-condemnatory one", would be necessary.
Another Western diplomat said that if Iran's report "does not include mention of the Iranian military's involvement in the entire program," then they would also be in non-compliance.
Fleming said the agency feels the report "appears to address all the areas of their nuclear program and the questions that we put to them."
But she said "a tremendous amount of follow-up work will be required to determine the report's completeness and accuracy."
IAEA officials have said it could take months to verify the Iranian report.
Iran has yet to meet IAEA demands for it to suspend uranium enrichment even though it has promised to do this.