A United Nations atomic agency official recently denied entry into Iran as part of a team investigating suspected bomb research is believed to be an American nuclear weapons expert, diplomatic sources said.
The International Atomic Energy Agency last month said Iran denied a visa for one member of an IAEA delegation that visited Tehran on Aug. 31 to try to advance a long-running inquiry into what the UN agency calls the possible military dimensions of the country's nuclear program.
It was the third time the person had been unable to obtain an entry permit, the Vienna-based IAEA said. It did not reveal the official's nationality or expertise.
But the sources, who spoke on condition of anonymity due to the sensitivity of the issue, said they believed he was a US national and an atomic arms expert. The IAEA declined to comment on Thursday.
It is important, the UN agency said in a Sept. 5 report on Iran's nuclear program, that "any staff member identified by the agency with the requisite expertise is able to participate in the agency's technical activities."