Rafael Grossi, director general of the UN's nuclear watchdog, will hold talks with Iranian officials on Sunday as the International Atomic Energy Agency considers action against Iran.
Iran invited Mr Grossi to Tehran before a meeting of the Vienna-based agency’s board of governors that starts on Monday.
IAEA envoys will discuss Tehran’s rapidly expanding nuclear programme. European diplomats have been considering whether to advance a resolution censuring Iran for its lack of co-operation with agency monitors.
Iran said that such a move would undermine negotiations focused on reining-in its nuclear output in return for relief from economic sanctions.
Those talks stalled over the summer and after Iran’s election of a hardline cleric, Ebrahim Raisi, as president.
Mr Grossi will meet the new head of Iran’s Atomic Energy Organisation, Mohammad Eslami, who replaced Ali Akbar Salehi in late August.
The two sides are likely to issue a joint statement, the state-run Islamic Republic News Agency reported, citing Kazem Gharibabadi, Iran’s envoy at the IAEA.
Mr Grossi is also expected to hold a press conference at Vienna airport on Sunday evening.
The IAEA official has recently been trying to set up talks with Mr Eslami to gauge Tehran’s willingness to restore expanded access for the agency’s monitors.
Mr Raisi, who was sworn in in August, cautioned the UN watchdog against “confrontation” this month.
On Saturday, Iran’s Foreign Ministry spokesman Saeed Khatibzadeh urged the IAEA to keep Sunday’s talks within “a technical and professional framework” and avoid politicising issues, according to the Fars news agency.
IAEA inspectors this week reported that Iran had increased its stockpile of enriched uranium close to the levels needed for weapons and was expanding its production