UN nuclear inspectors displayed new satellite imagery on Wednesday indicating that some small buildings had been dismantled and other possible clean-up work undertaken at an Iranian military site they want to visit.
One image from May 25 showed signs that "ground-scraping activities" had taken place at the Parchin facility, as well as the presence of a bulldozer, according to diplomats who attended a closed-door briefing by UN nuclear agency officials.
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This will likely further strengthen Western suspicions that Iran is "sanitizing" the site of any incriminating evidence before allowing the International Atomic Energy Agency (IAEA) into the complex. "It is very clear," one Western envoy said.
Iran's IAEA envoy, Ali Asghar Soltanieh, dismissed such accusations by Western officials, telling reporters after the briefing that "this kind of noise and allegations are baseless".
Wednesday's disclosure followed inconclusive talks between Iran and six world powers in Baghdad last week to address concerns about the nature of its nuclear activities.
The Parchin complex is at the centre of Western allegations that Iran has been conducting research and experiments relevant to developing a nuclear weapons capability. The Islamic Republic has repeatedly denied any such ambition.
Last week, the IAEA said in a report issued to member states that satellite images showed "extensive activities" at the facility southeast of Tehran.
Western diplomats said this was an allusion to suspected cleaning at Parchin. They have earlier cited other images showing recent activity at the site, including a stream of water, as suggesting Iran is trying to remove evidence.
At Wednesday's briefing for diplomats accredited to the Vienna-based agency, IAEA Deputy Director General Herman Nackaerts presented several satellite images, including from November and earlier this month, participants said.
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The image from late May indicated that two or possibly three small side buildings - in the same area as the main structure that is of interest to the UN agency - had been removed, diplomats said.
"It was like a demolition area," one Western diplomat said.
Nackaerts did not elaborate on what he believed was happening at the facility, apart from reiterating that the agency needed to go there to clarify the issue, diplomats said.
Iran, which denies Western accusations it is seeking to develop nuclear weapons capability, has dismissed charges aired about Parchin as "childish" and "ridiculous".
An IAEA report last November said that Iran had built a large containment vessel in 2000 at Parchin in which to conduct tests that the UN agency said were "strong indicators of possible (nuclear) weapon development."
It said a building was constructed "around a large cylindrical object." A large earth berm between the building containing the cylinder and a neighboring building indicated the probable use of high explosives in the chamber.
The IAEA said the vessel was designed to contain the detonation of up to 70 kg of high explosives. Diplomatic sources say the suspected tests likely took place about a decade ago.
Last week, Iranian media said the IAEA had not yet given good enough reasons to visit Parchin, which Iran says is solely a conventional military site.
"The reasons and documents have still not been presented by the agency to convince us to give permission for this visit," the head of the Atomic Energy Organization of Iran, Fereydoun Abbasi-Davani, was quoted as saying by Fars news agency.
Soltanieh made clear that the IAEA could only gain access to Parchin once a broader agreement had been reached on how to address the agency's questions about possible military aspects to Iran's nuclear program.
IAEA Director General Yukiya Amano said after visiting Tehran last week that he expected this framework agreement to unblock the agency's investigation would be signed soon, but Soltanieh said it had not yet been finalised.
Robert Kelley, a former senior IAEA official, said that if there were any uranium traces at the site the agency's inspectors were still likely to find them.
"If Iran is washing out the building and equipment outside, and there is actually uranium present, letting the uranium contaminated water run across the parking lot means the IAEA is going to have a 100% chance of finding it."
World powers who met Iran last week proposed ways of defusing concerns about its nuclear works, for example by having Tehran scale back uranium enrichment and accept more intrusive IAEA inspections in exchange for relief from economic sanctions.
No agreement was reached although the two sides decided on another meeting in Moscow on June 18-19.
But Iranian President Mahmoud Ahmadinejad said on Wednesday he did not expect the next talks to yield a breakthrough. "We are not expecting miracles at the next nuclear meeting in Moscow," he told France 24 television.
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