VIENNA - Iran and the UN nuclear agency have made progress in talks on the country's disputed nuclear programme but there are still many outstanding issues, the watchdog's chief inspector said on Monday.

Tero Varjoranta spoke to reporters a day after Iran agreed to start addressing suspicions that it may have worked on designing an atomic weapon, a potential breakthrough in a long-stalled investigation into Tehran's atomic activities.

Varjoranta said progress had been "good" but added: "There are still a lot of outstanding issues."