Deputy nuclear negotiator Javad Vaeedi, leading the Iranian team, declined to comment as he headed into the closed-door talks with Olli Heinonen, deputy director-general of the International Atomic Energy Agency.
IAEA chief Mohamed ElBaradei said earlier this month that Iran has scaled back its uranium enrichment program, suggesting there was a new willingness from the government to resolve the international deadlock over its nuclear stance.
The IAEA said Tuesday's talks in Vienna were an attempt to clarify "the open issues associated with the scope and content of Iran's enrichment program."
Iran insists its nuclear program is peaceful and geared solely toward producing electricity; the United States accuses it of covertly trying to build a nuclear weapon.
After the escalation of the conflict, Ankara will not be able to set Russia and the USA against each other in Syria. The President of Turkey has quarreled with all major players in Syria in four years after attempted coup in Turkey