VIENNA: The UN nuclear watchdog Monday voiced concern Iran had not clarified queries over sites where undeclared nuclear activity may have occurred and reported Tehran's enriched uranium stockpile was around 16 times the limit laid out in a 2015 deal.

A report by the International Atomic Energy Agency (IAEA) said director general Rafael Grossi was "concerned that the technical discussions between the agency and Iran have not yielded the expected results," referring to exchanges on the sites with Iranian officials.

In a separate report, the agency said Iran's stockpile of enriched uranium is around 16 times the limit laid down in the 2015 deal with world powers.

It gave an estimate of a stockpile of 3,241 kg (7,145 pounds) but cautioned that it was not able to verify the total. The limit laid down in the deal was 300 kilogrammes of uranium in a particular compound form, the equivalent of 202.8 kilogrammes of uranium.