"The Agency regrettably was unable to make any progress on the remaining issues which give rise to concerns about possible military dimensions of Iran?s nuclear program because of lack of cooperation by Iran," Mohamed ElBaradei said in the introductory statement to the opening session of the IAEA's 35-nation board.
The UN nuclear watchdog's chief called upon Iran to demonstrate increased cooperation and transparency to end the deadlock in a long-running dispute over Tehran's nuclear intentions.
"For the Agency to be able to make progress, Iran needs to provide substantive information and access to relevant documentation, locations and individuals in connection with all of the outstanding issues," ElBaradei said.
"I again urge Iran to implement all measures required to build confidence in the exclusively peaceful nature of its nuclear program at the earliest possible date and to unblock this stalemated situation," he added.
Iran is under three sets of relatively mild UN Security Council sanctions over its nuclear program. Western powers led by the United States, along with Israel, accuse Tehran of attempting to develop nuclear weapons. Iran says it needs its nuclear program for the peaceful generation of electricity.
The most recent UN Security Council resolution on Iran was passed on September 27, 2008. Although it did not include any new sanctions it called on Iran to fulfill its responsibilities under previous resolutions and IAEA commitments.
Tehran announced last week that the Islamic Republic had 6,000 operating centrifuges at a uranium enrichment facility at Natanz and was planning to install a total of 50,000 over the next five years.
Iran has consistently defied international demands to halt its nuclear program and insists it plans to use enriched uranium fuel produced at Natanz in its first domestically-built nuclear power plant, in the town of Darkhovin, which is scheduled to become operational in 2016.
