VIENNA U.N. inspectors found graphite and more uranium traces in test samples taken from a Syrian site Washington says was a covert graphite nuclear reactor almost built before Israel bombed it, officials said on Thursday.
The first word that graphite particles had turned up came with the release of the International Atomic Energy Agency's second report on Syria in three months. But U.N. officials familiar with it said the IAEA inquiry remained inconclusive.
Still, one senior U.N. official said the discovery of additional uranium traces was "significant." That, together with graphite traces that are undergoing more tests, raised pressure on Damascus to provide evidence for its denials of wrongdoing.
The IAEA's November report said the site bore features that would resemble those of an undeclared nuclear reactor.
Thursday's report said Damascus, in a letter to the IAEA this month, had repeated its position that the desert complex destroyed by Israel, known as al-Kibar or Dair Alzour, in September 2007 was a conventional military building only.
But Syria, it said, was still failing to back up its stance with documentation or by granting further access for IAEA sleuths to the bombed location and three others cited in U.S. intelligence handed to the U.N. watchdog last year.
Some diplomats said Syria might be playing a waiting game until it sees what U.S. President Barack Obama has to offer as part of his stated intent to engage foes including Iran, an ally of Syria with a disputed uranium enrichment program.
The United States says its information indicates the site was a reactor that was close to being built with North Korean assistance and designed to produce plutonium for atomic bombs.
The U.N. official said further analysis of swipe samples since November turned up around 40 more instances of processed uranium particles, adding to 40 registered three months ago.
He said some graphite traces had been found around the alleged reactor site and also by a water treatment plant 5 km away where equipment for the complex that was bombed to rubble by Israel had been stored temporarily.
"We are sure it is man-made graphite but not yet sure if it has specifications of nuclear-grade graphite," he said.
"If you find 40 uranium particles and then 40 more, this constitutes for us a significant finding, because we are now sure this is not just a simple contamination from a person who went to the site for a visit."
The IAEA report said the uranium contamination that turned up in soil samples was a chemically processed form of the mineral that was not the enriched variety used to run nuclear power plants or as fissile bomb material.
It was extremely unlikely, the report said, that the traces came with munitions Israel had used to smash the complex, as Syria has asserted. Depleted uranium is sometimes used to boost the penetrating power of munitions.
The report, to be debated by the IAEA's 35-nation governing board in early March, said the uranium element at issue was not in Syria's declared nuclear inventory. Syria's only official nuclear site is an old research reactor.
"The presence of the particles at Dair Alzour, imagery of the site available to the agency, and information about certain (nuclear-related) procurement activities need to be fully understood," the report said in its summary.
"Syria needs to be transparent by providing additional access to other locations alleged to be related to Dair Alzour. These measures, together with the sampling of destroyed and salvaged equipment and debris, are essential for the agency to complete its assessment," it added.
IAEA Director-General Mohamed ElBaradei again called on Syria to take such transparency steps as soon as possible.
He also urged Israel and other states to share information to help the IAEA probe, including satellite imagery, and agree to let inspectors share this information with Syria.
The IAEA report said Syria was still ignoring IAEA requests to let inspectors take swipe samples from rubble, shrapnel and any equipment that satellite pictures showed were removed from al-Kibar after Israel's air strike to undetermined locations.
Syria has also been asked to explain why it landscaped all four sites in question to alter their look after inspectors asked to examine them.
(Editing by Janet Lawrence)