By Francois Murphy
VIENNA (Reuters) -Iran has agreed to a visit by the U.N. nuclear watchdog this month to start giving answers the agency and its 35-nation board have long called for on the origin of uranium particles found at three sites, an IAEA report on Thursday seen by Reuters said.
Iran has yet to provide new material, however, and its offer came before next week's quarterly meeting of the International Atomic Energy Agency's Board of Governors at which diplomats say they expect Western powers to push for a resolution calling on Iran to cooperate, a move that Tehran usually bristles at.
Many diplomats see Iran's offer as a thinly veiled attempt to reduce support for another resolution after a similar one was passed in June, though in the absence of tangible progress there is little to suggest Tehran's move would scupper a push to formally criticise it at the board.
"(IAEA chief Rafael Grossi) takes note of Iran's proposal to hold a further technical meeting with senior Agency officials in Tehran before the end of the month, but stresses that this meeting should be aimed at effectively clarifying and resolving those issues," one of two confidential IAEA reports on Iran sent to member states on Thursday ahead of the board meeting said.
The IAEA "expects to start receiving from Iran technically credible explanations on these issues, including access to locations and material, as well as the taking of samples as appropriate", it added.
A senior diplomat said the Vienna-based agency hoped the meeting would be the start of a process leading to answers but concrete progress was also needed at the meeting itself.
Grossi told Reuters on Wednesday the meeting would be "in a couple of weeks".
The issue has become an obstacle in wider talks to revive Iran's 2015 nuclear deal with world powers, since Tehran has demanded a closure of the IAEA's investigation in those talks.
The IAEA has said it will not yield to political pressure and its job is to account for all nuclear material. The fact material that has not been accounted for appears to have been present at these sites is therefore an issue it must keep looking into until it is resolved.
"You can see the pattern of Iran is always similar. Every board there is something they try to do just before the board. Historically you see a pattern," the senior diplomat said when asked about the planned meeting in Tehran, pointing to previous meetings and offers preceding Board of Governors sessions.
Diplomats said Britain, France, Germany, known as the E3, and the United States planned to press ahead with another resolution.
One diplomat said that Iran's latest overtures were unlikely to change that stance. The latest resolution would aim to garner more support from board members than in June, while being tougher given Iran's ongoing non-compliance, the diplomat said.
The E3 and the United States will hold talks in Paris on Monday to discuss Iran ahead of the board meeting, two diplomats said.
State Department spokesperson Ned Price said he could not confirm any upcoming meetings, but said a U.S. team led by special envoy Rob Malley was in regular dialogue with Washington's European partners on Iran.
The 2015 deal restricted Iran's atomic activities in exchange for sanctions relief. In 2018, then-President Donald Trump ordered a U.S. withdrawal from the deal, reimposing U.S. sanctions against Tehran. Iran responded by breaching and going well beyond the deal's restrictions.
Iran has recently installed hundreds more advanced centrifuges, machines that enrich uranium, at its underground plants at Natanz and Fordow. The move increases the pace at which it can enrich.
The 2015 deal only lets Iran produce enriched uranium with more basic, first-generation centrifuges.
The other IAEA report, issued on Thursday and also seen by Reuters, showed Iran's stock of enriched uranium had shrunk slightly, decreasing by around 267 kg to an estimated 3,673.7 kg, still far beyond the 202.8 kg allowed by the deal.
Its stock of uranium enriched to 60% purity, close to the roughly 90% weapons-grade level, grew by an estimated 6.7 kg to more than 62 kg. That is more than enough, if refined further, for one nuclear bomb. Iran denies seeking nuclear weapons, saying its nuclear technology is solely for civil purposes.
(Additional reporting by John Irish, Arshad Mohammed and Humeyra Pamuk; Editin by Toby Chopra and Deepa Babington)