The head of the UN nuclear agency has arrived in Tehran on a key mission that could lead to the resumption of probes on whether Iran has secretly worked on a nuclear weapon, the Associated Press reports.

International Atomic Energy Agency chief Yukiya Amano and his two aides landed early Monday, May 21 morning in Iran but where quickly whisked away from the Tehran airport.

They are to meet Iran's top nuclear negotiator, Saeed Jalili, as well as the Foreign Minister and other Iranian officials later in the day.

The visit is focused on getting Iran to agree to terms that will allow IAEA probes of suspect Iranian sites. Tehran denies having worked on atomic weapons.

Amano's trip comes ahead of another round of nuclear talks between the six world powers and Iran on Wednesday in Baghdad.