The head of the U.N. nuclear watchdog says Iran is complying with the 2015 deal with major world powers aimed at preventing the country from building nuclear weapons.

Yukiya Amano made his assessment in a regular update to the International Atomic Energy Agency's board of governors, confirming a confidential report distributed to member states last month.

He said on Monday that "Iran is implementing its nuclear-related commitments under the Joint Comprehensive Plan of Action," referencing the official name of the 2015 deal. The U.S. unilaterally withdrew from the deal last year and re-imposed sanctions.

The other signatories - Germany, France, Britain, Russia and China - are trying to keep alive the deal, which offered Iran economic incentives.

On the issue of North Korea, Amani said that IAEA was "ready to undertake varification and monitoring activities" there "if a political agreement is reached among countries concerned."