The leader of an al-Qaida umbrella group in Iraq threatened to wage war against Iran unless it stops supporting Shi'ites in Iraq within two months, according to an audiotape. Abu Omar al-Baghdadi, who leads the group Islamic State in Iraq, said his Sunni fighters have been preparing for four years to wage a battle against Shi'ite-dominated Iran. "We are giving the Persians, and especially the rulers of Iran, a two-month period to end all kinds of support for the Iraqi Shi'ite government and to stop direct and indirect intervention ... otherwise a severe war is waiting for you," he said in the 50-minute audiotape released Sunday. The tape, which could not be independently verified, was posted on a Web site commonly used by insurgent groups. Iraq's Shi'ite-led government is backed by the US but closely allied to Iran. The United States accuses Iran of arming and financing Shi'ite militias in Iraq - charges Teheran denies.