The UN atomic agency unveils its latest report on Iran's disputed nuclear drive on Monday, with world powers warning Tehran is "running out of time" to respond to a UN-brokered offer to end the standoff.
The International Atomic Energy Agency report will take stock of Iran's uranium enrichment activities in spite of international sanctions and detail findings from an October visit to a previously secret atomic site at Qom.
President Barack Obama on Sunday won the strongest backing yet from Russian counterpart Dmitry Medvedev on Iran, with the US leader expressing frustration that Tehran had yet to answer an offer to enrich uranium outside of Iran.
"Unfortunately, so far at least, Iran has been unable to say yes" to the proposal, Obama said after talks with Medvedev in Singapore. "We now are running out of time with respect to that approach."
Russia, which has the strongest ties with Tehran of any big power, has traditionally been unwilling to punish Iran with tough measures. But Medvedev said that Tehran risked sanctions if the crisis continued.
He said Moscow was "not completely happy about the pace" of efforts to resolve the crisis.
"In case we fail, the other options remain on the table, in order to move the process in a different direction," he said in a reference to new UN sanctions against Tehran.
Russia, like the United States, is a veto-wielding UN Security Council permanent member, and its support is crucial if US warnings of tough sanctions against Tehran are to carry weight.
Obama described as "fair" the proposal offered to Iran, which would see states -- including Russia -- help Tehran to further enrich Iranian uranium for delivery to a research reactor.
Referring to sanctions, he said that "we will begin to discuss and prepare for these other pathways" as Tehran could not be counted on to fulfil its international obligations.
The West suspects Tehran is trying to develop a nuclear weapon under cover of its civilian nuclear energy programme. Iran vehemently denies the claims while Russia has said there is no evidence to support the accusations.
Turkish Energy Minister Taner Yildiz said on Saturday that Ankara was in talks with the IAEA to enrich Iran's uranium and that his country saw no objection to doing so.
IAEA Secretary General Mohamed ElBaradei, whose mandate finishes at the end of November, is to chair his last board of governor's meeting on November 26, during which Monday's report will be discussed.