U.N. nuclear watchdog chief Yukiya Amano will visit Iran on Sunday to try to obtain more Iranian cooperation with the agency's long-running inquiry into Tehran's nuclear activities, the IAEA said on Friday.
He will visit ahead of an Aug. 25 deadline for Iran to provide information relevant to the International Atomic Energy Agency's investigation into suspicions that Iran may have researched how to build a nuclear bomb, an accusation it denies.
Diplomatic sources told Reuters two weeks ago that the Vienna-based IAEA was concerned about Iran's failure to make good on pledges of more transparency.
Western officials say Iranian clarifications would also advance efforts by six world powers to negotiate an end to a decade-old standoff over the Islamic Republic's nuclear programme, suggesting some sanctions relief may depend on it.
The Islamic Republic says it is enriching uranium solely as a peaceful project to generate electricity, not to accumulate fissile material for a potential atomic bomb, as the West suspects.
It rejects such suspicions as based on false and fabricated information from its enemies but has promised, since pragmatist Hassan Rouhani became president in mid-2013, to work with the Vienna-based U.N. agency to clear them up.