The UN atomic watchdog and Iran hailed Tuesday "productive" and "constructive" talks, in the latest possible sign of Tehran's willingness to ease international concerns about its nuclear work.
Iran's envoy to the International Atomic Energy Agency said he presented a new proposal -- aimed at clearing up allegations of past nuclear weapons research -- that he hopes will "open a new chapter of cooperation".
The two sides will meet again in Tehran on November 11, a few days after parallel talks with the P5+1 group of six world powers -- the five permanent members of the UN Security Council plus Germany -- in Geneva on November 7-8.
The two-day meeting in Vienna was one of a series of gatherings in the Austrian capital this week meant to prepare the groundwork for that Geneva meeting.
"Iran presented a new proposal on practical measures as a constructive contribution to strengthen cooperation and dialogue with a view to future resolution of all outstanding issues," the IAEA's new chief inspector Tero Varjoranta said.
No details of the new proposal were given but Varjoranta called the talks "very productive". Iran's envoy Reza Najafi said they were "constructive".
The IAEA conducts regular inspections of Iran's nuclear activities but it also wants to probe evidence suggesting that prior to 2003, and possibly since, Iranian scientists conducted experiments aimed at developing a nuclear arsenal.
Iran has consistently denied this, saying the IAEA's claims are based on faulty foreign intelligence from the likes of the CIA and Israel's Mossad that it complains it has not even been allowed to see.
Ten meetings between Iran and the IAEA since a major report from the UN body in November 2011 have failed to make any progress, but Hassan Rouhani's election as Iranian president in August has precipitated a change in tone.
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Rouhani has also created optimism for progress in Iran's parallel talks with world powers, which are focused more on Iran's current activities, most notably uranium enrichment.
Iran's Foreign Minister Javad Zarif held a landmark meeting with US Secretary of State John Kerry during the UN General Assembly in September, when US President Barack Obama and Rouhani also shared a historic phone call.
Iran denies seeking or ever having sought to build the atomic bomb while steadily expanding its nuclear programme over the years in defiance of multiple UN Security Council resolutions and sanctions.
Some experts warn that Iran may next year reach "critical capacity" -- the point at which it could, in theory, process sufficient weapons-grade uranium for a bomb before being detected.
In Geneva on October 15-16, Iran presented to the P5+1 a new proposal that chief negotiator Abbas Araqchi said could settle the dispute "within a year".
But after many false dawns in the long-running standoff, it remains to be seen whether a deal that satisfies both sides is possible.
Western countries want Iran to scale back its nuclear activities and to grant the IAEA greater inspection rights, while Tehran, insisting on its "right" to uranium enrichment, wants sanctions relief.
Watching closely is Israel, which is widely believed to have its own nuclear arsenal and has refused to rule out bombing its arch-rival, while warning against what it sees as an empty "charm offensive" by the Islamic republic.
Mark Hibbs, analyst at the Carnegie Endowment for International Peace, said before this week's talks that Iran cooperating with the IAEA would "add confidence and momentum" to the Geneva talks.
"Until now a lack of agreement between the IAEA and Iran has been an obstacle in negotiations between Iran and the P5+1," Hibbs told AFP.