Iraq's top Shi'ite cleric Ali al-Sistani told his aides in Najaf on Friday to prepare to accept the keys to the mosque held by rebel cleric Moqtada al-Sadr, a London-based spokesman for Sistani said. "His office in Najaf has been instructed to receive the sealed envelope containing the keys to the mausoleum and holy shrine when (al-Sadr's supporters) vacate," he said. The spokesman added he was unaware if the instructions had been communicated to Sadr's followers in Najaf.