VIENNA, Austria -- Iran is signalling that it will co-operate this weekend with U.N. experts visiting the country to investigate alleged nuclear weapons activity it has steadfastly denied, a potentially promising step in a probe that has been stalled for six years.
But with Iran still denying any attempt to make such arms, the investigators must tread carefully.
As the U.N.'s International Atomic Energy team arrived in Tehran on Friday, the state IRNA news agency cited Iranian atomic energy organization spokesman Behrouz Kamalvandi as saying his country is ready to answer all questions raised by the U.N. agency.
IRNA did not elaborate, and such pledges have been made before. However, a senior diplomat from an IAEA member nation cited a ranking Iranian official as telling him and other senior diplomats that Iran was specifically ready to engage on the weapons program suspicions with the U.N. experts.
The diplomat demanded anonymity because he wasn't allowed to discuss his private meeting with the Iranian official.
Iran has denied any interest in -- or work on -- nuclear weapons since the IAEA started to focus on its atomic activities. Specific attempts to probe the alleged weapons program first launched in 2007 have made little progress.
Iran appears to be suggesting it will go into detail on the big topic, an issue it has previously said was not in the agency's purview or was based on doctored intelligence. If successful, it will be the first of what the agency hopes will be a series of increasingly deeper investigations into the nuclear weapons allegations.
The U.S. and its allies are pushing the IAEA for progress. At the same time, too much pressure on Iran at the weekend talks between the agency and Iranian officials could push Tehran back into its shell of secrecy.
That, in turn, may impact negatively on parallel talks between Iran and six world powers seeking to eliminate fears Tehran may use its nuclear programs to make weapons. It has agreed to curb its atomic activities in exchange for sanctions relief.
Those talks are off to a promising start with both sides planning to meet Feb. 18 to try to translate an interim deal into a permanent agreement. But Olli Heinonen, who formerly headed the IAEA's Iran probe, says that -- with distrust still high on both sides -- a final deal can be sealed "only if uncertainties over Iran's military nuclear capability are properly addressed."
Another diplomat said that the IAEA team was carrying a list of alleged weapons-related experiments that it would present to the Iranian negotiating team for discussion. Among them, were:
-- indications that Iran has conducted high explosives testing and detonator development to set off a nuclear charge, as well as computer modeling of a core of a nuclear warhead.
-- suspected preparatory work for a nuclear weapons test, and development of a nuclear payload for Iran's Shahab 3 intermediate range missile -- a weapon that can reach Israel.
--information that Iran went further underground to continue work on nuclear weapons development past 2003, the year that U.S. intelligence agencies believe such activity ceased.
Iran has up to now denied the allegations, first published in detail by the IAEA in November 2011. It has dismissed them as inaccurate or outright false, based on doctored intelligence from the U.S., Israel and other Iran adversaries.
The agency is seeking access to individuals, documents and sites linked to these and other alleged nuclear weapons-related work.
The second diplomat, from a Western nation, also demanded anonymity because he wasn't authorized to share his information. He said the U.S. and its Western allies had made clear to IAEA chief Yukiya Amano that they expected progress on clearing up the weapons allegations.
A third diplomat, also from a Western country said agency experts were planning to allow Iran to ease into co-operation on the weapons allegations by asking first for less sensitive information. He declined to give details and demanded anonymity because he wasn't authorized to discuss confidential negotiating tactics.
In Tehran, meanwhile, Iran's Supreme Leader urged officials Saturday not to pin hopes for economic recovery on the sanctions relief from the nuclear deal reached with world powers.
Ayatollah Ali Khamenei also called on critics of the interim nuclear deal achieved on Nov. 24 in Geneva to be fair and give time to President Hassan Rouhani to pursue his policy of engagement with the outside world.
"The only solution to the country's economic problems is to employ (Iran's) infinite domestic capacities, not to pin hopes on the lifting of sanctions. No expectations from the enemy," Khamenei told army officers in Tehran.
Khamenei also defended Rouhani against hardliners in Iran who think the deal gives away too much for too little in return,
"No more than a few months have passed since the (Rouhani) government took office. Authorities should be given the opportunity to push forward strongly. Critics should show tolerance toward the government," he said in comments posted on his website, leader.ir.
Khamenei's support is crucial for Rouhani's diplomatic success in negotiations with the six-nation group -- the United States, Russia, China, Britain, France and Germany.
Associated Press writer Ali Akbar Dareini in Tehran, Iran, contributed to this report.
