Iran completed a "constructive" round of talks with the United Nations' nuclear watchdog on Tuesday and further meetings are planned in the future, the semi-official Fars news agency reported.

"Talks between Iran and the visiting team of inspectors from the International Atomic Energy Agency (IAEA) were constructive and ... the two sides agreed to continue the talks," Fars quoted an unnamed source as saying.

Senior United Nations nuclear inspectors headed to Tehran on Saturday to hold talks with Iranian officials over suspicions that the Islamic state is seeking atomic weapons.

The West suspects that Iran's uranium enrichment activities have military aims but Tehran says they are for peaceful electricity generation.

The Fars report said the date of future talks between Iran and IAEA had been set, but did not give details.