The UN nuclear watchdog's governing body began meeting Monday (June 15th) as a row brews over Iran's refusal to allow access to two sites where nuclear activity may have occurred in the past.
The Vienna-based International Atomic Energy Agency (IAEA) expressed "serious concern" in a report earlier this month that Iran has been blocking inspections at the sites.
The Board of Governors, one of the agency's policy-making bodies, is expected to discuss the report during its meeting. If it passes a resolution critical of Iran, this would be the first of its kind since 2012.
Even though the two sites are not thought to be key to Iran's current activities, the agency says it needs to know if past activities going back almost two decades have been properly declared and all materials accounted for.
The report detailed efforts made by IAEA officials to get access to the locations.
In a statement to the Board of Governors, IAEA director general Rafael Grossi called on Iran "to co-operate immediately and fully with the agency, including by providing prompt access to the locations specified by us".
Brink of collapse
The latest row over access comes as a landmark deal between Iran and world powers in 2015 continues to unravel.
Under the deal, known as the Joint Comprehensive Plan of Action (JCPOA), Iran committed to curtailing its nuclear activities in return for sanctions relief and other benefits.
But Iran has slowly abandoned its commitments, and its stockpile of enriched uranium is now almost eight times the limit fixed in the accord, according to an IAEA assessment published earlier this month.
The level of enrichment is still far below what would be needed for a nuclear weapon, however, and the IAEA says it continues to have access to all the facilities needed to monitor Iran's current nuclear activity.
Last month, the US, which withdrew from the JCPOA in May 2018, said it was ending sanctions waivers for nations that remain in the Iran nuclear accord.
This move is likely to have most impact on Russian firms working on Iran's nuclear programme.
Iran is also concerned that the US is pushing for an extension to an international arms embargo against it which is set to be progressively eased from October.