The head of the International Atomic Energy Agency (IAEA) has arrived in Iran for a visit aimed at improving cooperation on the country's nuclear activities.
IAEA Director-General Rafael Grossi is scheduled to hold talks with high-level Iranian officials over the next two days, including President Hassan Rohani and Ali Akbar Salehi, head of Iran's Atomic Energy Organization.
It is Grossi's first trip to Iran since taking over the IAEA leadership eight months ago and comes amid a mounting standoff between the Vienna-based UN agency and Tehran over access to two sites where nuclear activities might have occurred and with the United States pressing for reimposing UN nuclear-related sanctions against Tehran.
"My objective is that my meetings in Tehran will lead to concrete progress in addressing the outstanding questions that the Agency has related to safeguards in Iran and, in particular, to resolve the issue of access," Grossi said ahead of his trip.
The IAEA's board of governors passed a rare resolution in June calling on Iran to provide access to two sites where nuclear activities may have taken place in the past.
The resolution, the first of its kind since 2012, demanded that Iran "fully cooperate" and "satisfy the agency's requests without any further delay," including by providing "prompt" access to the two sites in order to clarify whether undeclared nuclear activity took place there during the early 2000s.
At the time, Grossi accused Iran of denying access to the two locations for six months, and said that for almost a year "it has not engaged in substantive discussions to clarify our questions related to possible undeclared nuclear material and nuclear-related activities."
Iran maintains the IAEA has no legal basis to inspect the sites in question.
The IAEA-Iran standoff comes with the United States pressing for reimposing UN sanctions lifted as part of a 2015 nuclear deal between Tehran and world powers. Washington exited the agreement more than two years ago and reimposed unilateral sanctions on Iran.
U.S. Secretary of State Mike Pompeo last week formally launched the monthlong process of activating the nuclear accord's "snapback" mechanism aimed at reimposing UN sanctions on Iran, citing Iranian violations of the deal.
But the U.S. move faces opposition at the Security Council, where other members have questioned the United States' right to do it since Washington withdrew from the nuclear pact.
The United States claims it remains a "participant" in the accord because it was listed as such in the UN resolution that enshrined it.