The arrival of the U.N. delegation in Tehran came less than a week after the latest United States intelligence estimate said Iran had abandoned its nuclear weapons program in 2003, Alalam reported.

Iran's envoy to the IAEA told the Fars News Agency the agenda included a discussion of the origin of traces of uranium traces discovered at one site.

Despite opposition from the United States and key European allies, Iran has vowed to continue its enrichment of uranium saying the program is geared toward producing electricity.

Two sets of economic sanctions have been imposed on Iran by the U.N. Security Council at the behest of Western countries that claim Tehran sought to develop a nuclear weapon.