Vienna - The UN nuclear watchdog and Iran ended a meeting on Monday without giving statements on the outcome, leaving unclear whether progress was made in efforts to help allay international concern over Tehran's nuclear programme.
Under a transparency and cooperation pact agreed between Iran and the International Atomic Energy Agency in November, Iran was to take seven practical measures by May 15 in a phased process, including more IAEA access to nuclear-related sites.
Diplomatic sources told Reuters on Friday that the IAEA was seeking further clarification from Iran about one of those steps, concerning information about fast-acting detonators that can have both military and civilian applications.
Iran says it has already implemented the seven steps - including access to two uranium sites - but the sources suggested the IAEA still wanted more information about the so-called Explosive Bridge Wire (EBW) detonators.
Western powers suspect Iran has been trying to develop the capability to make nuclear weapons. Iran rejects the allegation, saying its programme is a peaceful energy project.
Monday's meeting took place a day before the Islamic Republic and six world powers on Tuesday resume, also in the Austrian capital, negotiations on a broad diplomatic settlement of the decade-old nuclear dispute.