BAGHDAD, Jan 30 (Reuters) - A Shi'ite Muslim messianic cult, whose leader was reported to have been involved in fighting with U.S. and Iraqi troops, said on Tuesday it played no part in the battle in which about 260 people were killed. Followers of Imam Ahmed al-Hassan al-Yamani, who styles himself the messenger or envoy of the Mahdi, a messiah-like figure in Islam, said theirs was a peaceful movement not linked to the "Soldiers of Heaven" who fought the day-long battle near the holy city of Najaf on Sunday. Conflicting accounts from Iraqi political and security sources have thickened the...