Radical Shi'ite cleric Muqtada al-Sadr has threatened by the end of the week to lift a six-month cease-fire that has widely been credited with helping to reduce violence around Iraq by 60 percent in the past half-year, a spokesman and another official said Wednesday. Sheik Salah al-Obeidi, a spokesman for al-Sadr in Najaf, said that if the cleric failed to issue a statement by Saturday saying that the cease-fire was extended "then that means the freeze is over." Al-Sadr's Mahdi Army is among the most powerful militias in Iraq. According to al-Obeidi, this "has been conveyed to all Mahdi Army members nationwide." The threat was confirmed by another al-Sadr official, who asked not to be named because he was not authorized to speak to the media.