Iran conducted activities "relevant" to developing nuclear weapons at least until the end of 2003, the UN atomic watchdog said Thursday in a major report on Tehran's past activities. "The agency assesses that a range of activities relevant to the development of a nuclear explosive device were conducted in Iran prior to the end of 2003 as a co-ordinated effort, and some activities took place after 2003," the IAEA said, adding however that there were no signs of any such work after 2009.