United Nations inspectors are analyzing further evidence taken from a nuclear research plant in Syria's capital Damascus where unexplained uranium traces were found, the UN's nuclear watchdog said on Friday.
But the International Atomic Energy Agency said Syria was still blocking follow-up access to the desert site of what U.S. intelligence reports said was a nascent, North Korean-designed nuclear reactor meant to yield atomic bomb fuel, before Israel bombed it to pieces in 2007.
In June, the Vienna-based IAEA said particles of processed uranium showed up in swipe samples taken by inspectors at the research reactor in Damascus and that it was checking for a link to traces retrieved from the bombed Dair Alzour site.
The IAEA said on Friday it carried out an inventory verification check at the Damascus Miniature Neutron Source Reactor (MNSR) in July, collecting environmental samples of what Syria said was the source of the uranium particles.
The samples were now being analyzed with the results likely to be ready by November.
U.S. analysts have said the IAEA's findings raised the question of whether Syria used some natural uranium intended for the alleged reactor at Dair Alzour for experiments applicable to learning how to separate out plutonium from spent nuclear fuel.
Syria's only declared nuclear site is the Damascus research reactor and, unlike Iran, it has no known nuclear energy-generating capacity.
Syria has said that the uranium traces at Dair Alzour came with Israeli munitions used in the strike and that Israel's target was a conventional military building.
Damascus denies hiding anything from the IAEA. But the agency says Syria is withholding documentation and blocking access that inspectors need to clarify the case.
Syria, an ally of Iran which is under IAEA investigation over nuclear proliferation suspicions, has denied ever having an atom bomb program and said the intelligence is fabricated.
Damascus has complained that its case is being mishandled and questioned the IAEA's grasp of physics.
But the IAEA said earlier this year inspectors had found enough traces of uranium in soil samples collected in June 2008 at Dair Alzour to constitute a "significant" find.
They subsequently detected similar "manmade" uranium particles in test swipes at the Damascus research site which the IAEA knew about and checked routinely.
Friday's report said Syria, citing national security grounds, was still refusing IAEA requests for return visits to Dair Alzour and a look at three military sites, whose appearance was altered by landscaping after the IAEA asked to check them.
"However, there is no limitation in comprehensive safeguards agreements (between the IAEA and member states) on agency access to information, activities or locations simply because they may be military related," the report said.
"The fact that the agency has found particles of nuclear material of a type which is not in the declared inventory of Syria underscores the need to pursue this matter."
IAEA Director-General Mohamed ElBaradei has said the allegations are serious and must be clarified. But he has also rebuked the United States and Israel for failing to alert the UN watchdog about the site before it was bombed to rubble, saying this had made the search for truth extremely difficult.
Friday's report said ElBaradei had urged states including Israel which "may possess information relevant to the agency's verification, including information which may have led them to conclude that the installation in question had been a nuclear reactor, to make such information available to the Agency."
Above all, the IAEA wants to examine equipment and rubble removed from Dair Alzour before investigators could get there.
But Syria told the IAEA the debris had already been disposed of so it was impossible to fulfill the agency's request, originally made over a year after the bombing, the report said.
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