Six major powers begin Iran nuclear meeting: U.S. Official

VIENNA (Reuters) - Six major powers seeking to negotiate an agreement to limit the Iranian nuclear program began a meeting in the early hours of Tuesday, a U.S. official said. The official, who spoke on condition of anonymity, said Iran did not take part in the meeting. The powers - Britain, China, France, Germany, Russia and the United States - are seeking to strike an agreement under which Iran would constrain its nuclear program in return for relief from economic sanctions. (Reporting by Loui