Iran on Sunday rejected claims presented to the UN atomic watchdog that it may have been studying how to develop a nuclear weapon, a day ahead of a visit by a top International Atomic Energy Agency (IAEA) official. "These are nothing but baseless and unfounded allegations," Foreign Ministry spokesman Mohammad Ali Hosseini told reporters. "The peaceful nature of Iran's nuclear programme has already been proven." IAEA deputy director general Olli Heinonen is due in Tehran on Monday for talks with officials on the alleged weaponisation studies, the Vienna-based atomic agency announced on Saturday.