Vienna: The United States on Wednesday demanded Syria give free rein to UN nuclear investigators after diplomats said Damascus would bar access to some sites Washington believes are linked to a secret atomic reactor.

The United States says Syria was close to completing a reactor with North Korean help that could have yielded plutonium for nuclear arms before it was bombed by Israel last September.

The UN nuclear watchdog began an inquiry after receiving US intelligence documentation in April.

International Atomic Energy Agency director Mohammad Al Baradei said on Monday that Syria, which had not responded to IAEA requests for explanations since the bombing, would allow in United Nations inspectors on June 22-24 to pursue the inquiry.

Informed diplomats said Syria would let inspectors examine the Al Kibar site in its northeast desert, but not go to three other locations believed to house facilities or equipment for producing plutonium from fuel from the reactor.

That prompted Gregory Schulte, US ambassador to the IAEA, to demand that Syria not hinder agency investigators in any way.

Rigorous investigation

"The United States welcomes the announcement that the IAEA will visit Syria and stands ready to support a rigorous IAEA investigation into Syria's clandestine nuclear activities," Schulte said in a statement sent to Reuters.

"It is imperative that Syria fully cooperate with the IAEA and in no way hinder the investigation either by further delaying an inspection or by refusing the IAEA unfettered access to any site requested by the IAEA," he said.

But a senior Syrian official told an Arab League meeting outside an IAEA governors' conference in Vienna on Tuesday that the IAEA trip would go ahead and inspectors would get access to the Al Kibar site, diplomats in the meeting said.

West backed over Iran

Syrian Atomic Energy Agency chief Ebrahim Othman told them, however, that Damascus would not permit checks of other sites Washington had urged inspectors to examine as possible places for processing nuclear material, diplomats said.

They said the position of Syria, which is in a state of war with Israel, was that the other sites were off-limits military installations essential to national security and irrelevant to the IAEA because they had no nuclear connection.

Meanwhile, developing nations joined the West in throwing their weight behind the UN nuclear watchdog's attempt to get Iran to clarify intelligence alleging that it secretly researched ways of making atom bombs. It was a rare sign of convergence on the International Atomic Energy Agency's 35-nation board of governors after an inspector report on Iran that was tougher than previous ones and a call by the IAEA chief for "full disclosure" by Tehran.