The UN's atomic watchdog says it is willing to make a deal on inspections with Iran's new leadership that could renew nuclear diplomacy with Tehran.
Rafael Grossi, the head of the International Atomic Energy Agency, has spoken to Iran's acting chief diplomat since a helicopter crash killed president Ebrahim Raisi and foreign minister Hossein Amirabdollahian on May 19.
Mr Grossi told the IAEA's ruling board on Monday that Iran had agreed to resume talks postponed by a mourning period.
Under an agreement, the IAEA could be given wider access to nuclear centres in Iran, which is increasing its stockpile of enriched uranium.
Britain, France and Germany have submitted a wide-ranging draft resolution against Iran to the UN nuclear watchdog's 35-nation board of governors to be voted on this week, Reuters reported later on Monday.
The European powers are pushing for the resolution despite US concerns that the move could lead Iran to respond by escalating its nuclear activities.
Although Iran denies seeking a nuclear weapon, the IAEA says it cannot confirm its intentions are peaceful while its monitoring is incomplete.
Alarm bells have been rung at the IAEA's Vienna headquarters by a recent Iranian warning that its nuclear doctrine could change if it is threatened by Israel.
Iran has also indicated that it will respond if the US and European powers push a new resolution through the IAEA's board condemning Tehran's activities.
Mr Grossi said that any wider resumption of talks, such as a new version of the 2015 deal that lifted sanctions on Iran, would need the IAEA to have full oversight.
Iran has openly stopped complying with limits on its nuclear activity since the US pulled out of the Joint Comprehensive Plan of Action in 2018.
Obstruction by Tehran means the agency is "now, in some areas, guessing" as to Iran's use of centrifuges and other nuclear activities, Mr Grossi said.
It is hoped that "at some point there will be a return to diplomacy, a return to a general framework, call it JCPOA version two, or version three, or any other name", he said.
"For that to happen, the agency will have to be able to say what the basis is, and what I have been explaining to my Iranian counterparts is that if I am not able, I won’t.
"I will not sign on any report saying that Iran has a number of centrifuges, or parts for centrifuges, if I cannot see [them]."
The IAEA is also pressing Iran to explain the presence of uranium particles at two undeclared sites, Varamin and Turquzabad.
The board was told there had been "no progress" on that front due to Iran failing to provide "technically credible explanations".
Mr Grossi visited Tehran in early May to discuss how the IAEA could have "more access, more visibility" at Iranian sites.
A team of IAEA technical experts was sent to Tehran last month to discuss further details but had to pack its bags after the helicopter crash on May 19.
The crash in heavy fog in north-west Iran killed the president, the foreign minister, and two other officials as well as bodyguards and flight crew.
Mr Grossi said he had told Iran's acting Foreign Minister Ali Bagheri Kani of the IAEA's desire to "continue working" in a call last Friday.
The IAEA hopes its inspectors could "have more cameras, have more online systems, have perhaps more frequency of visits, have visits to places that we are not visiting at the moment", he said. "This is the idea."
