The head of the UN nuclear watchdog has arrived in Tehran, voicing optimism about reaching agreement on Iran's controversial nuclear programme.
Yukiya Amano, of the International Atomic Energy Agency is due to hold talks with Iran's chief nuclear negotiator, Saeed Jalili.
His visit comes ahead of a meeting in Baghdad between six world powers and Iran on Wednesday.
Iran denies claims by Western nations that it is developing a nuclear weapon.
Tehran has refused to provide the IAEA access to relevant sites, officials and documents for more than four years.
Western diplomats quoted by Reuters say Amano would only visit Tehran if he believed a framework agreement to grant inspectors greater access was close.
The UK, China, France, Russia, the United States and Germany are all due to take part in the Baghdad talks.