United Nations inspectors have arrived in Iran to clarify "outstanding substantive issues" on the country's nucear development activities.
Chief inspector Herman Nackaerts of Belgium is leading the team from the International Atomic Energy Agency, according to Iran's official Islamic Republic News Agency (IRNA).
The team, which arrived early Sunday, is scheduled to hold talks later in the day with Iranian officials, and will remain in the country until Tuesday.
Also among the delegation is the IAEA's second-highest official, Rafael Grossi.
The visit comes in the wake of a report by the U.N. agency in November 2011 warning of evidence that Iran is intent on developing a nuclear weapon of mass destruction.
Iran has insisted that its nuclear development activities are aimed at peaceful domestic purposes only -- but it has refused to modify or stop them, and has maintained secrecy about its programs at the highest levels.
It is expected that the team of inspectors will visit the underground Fordow uranium enrichment site, IRNA reported.
The facility, located south of Tehran, near Qom, is situated deep within a mountain bunker, and enables the Islamic Republic to enrich uranium to 20 percent purity -- a point at which the nuclear fuel is able to be used to arm a primitive nuclear weapon.