Iran's deputy foreign minister said he had made proposals to the UN nuclear watchdog chief on Monday after pledging "a new approach" to easing international concerns about indications of illicit nuclear bomb research by Tehran.
UN inspectors want to resume an investigation, long stymied by Iranian non-cooperation, into what it calls the "possible military dimensions" of the Islamic Republic's nuclear programme. Tehran says it is enriching uranium solely for electricity generation and medical treatments.
Hopes of overcoming the stalemate between Iran and the International Atomic Energy Agency over the nature of the nuclear programme have risen since the election of a moderate president committed to easing Tehran's isolation.
Deputy Foreign Minister Abbas Araqchi said he had had "very useful" discussions with IAEA Director General Yukiya Amano and had made proposals to him to be addressed in detail by senior IAEA and Iranian experts later in the day.
"I am very hopeful that we can come out with a good result," Araqchi told reporters in Vienna.
Araqchi's session with Amano was the first high-level IAEA-Iranian meeting since Iranian President Hassan Rouhani took office in August pledging conciliation in the place of confrontation in the Islamic Republic's foreign relations.
"It is very important for all of us that we can show concrete progress," Amano said, seated across a table from Araqchi at IAEA headquarters as the talks began.
"We think this is the time to take a new approach to resolving (questions) between Iran and the IAEA and look to the future for further cooperation in order to ensure the peaceful nature of Iran's nuclear programme," Araqchi said.
He gave no details, although added, "It is peaceful and it will remain peaceful for ever."
Expectations for Monday's Vienna talks were relatively high and diplomats believed Iran might soon offer some concessions, perhaps by allowing UN inspectors to visit its Parchin military base southeast of Tehran - long an IAEA priority.
Taking advantage of the diplomatic opening enabled by Rouhani, Iran and six world powers are pursuing separate negotiations towards a broader political settlement to the dispute to head off any risk of a new Middle East war.
Their last meeting was held in October in Geneva, and another one is scheduled for November.
An end to Iran's higher-grade enrichment of uranium is a central demand of the powers. Refining uranium to 20 percent is sensitive as it is a relatively short technical step to raise that to the 90 percent needed for making a nuclear weapon.
Rouhani has promised to engage with the West in return for an easing of economically damaging sanctions against Iran, a dramatic departure from eight years of ideological belligerence under hardline conservative predecessor Mahmoud Ahmadinejad.