"Iran has refused five times to let a U.N. atomic agency official, believed to be an American bomb expert, into the country as part of a team investigating its disputed nuclear activities, diplomats said...
The IAEA said Iran did not issue a visa for one member of the U.N. agency's team visiting Tehran last month, adding it was the fourth time this individual had been denied access. It did not specify the time period for the previous refusals.
In addition, diplomatic sources said the same person was not able to travel to the Iranian capital for another IAEA trip on Nov. 2 to press for progress in the investigation.
The IAEA did not identify the individual or reveal his or her nationality. Diplomats last month said they believed he was a U.S. national and an atomic arms expert."