President Hosni Mubarak, in a rare acknowledgment of deepening tensions between Egypt's Muslims and Christians, exhorted Muslim scholars on Saturday to teach tolerance and shun extremism. He said the country needed "a religious discourse that cuts away intrigues and backbiting among Muslims and Christians - to preserve Egypt's stability, social fabric and national unity." The 77-year-old Mubarak issued the call to hundreds of Muslim clerics and scholars at Al-Azhar University, the world's highest seat of learning for Sunni Muslims. He spoke at the Lailat al-Qadr ceremony, which mark's God's revelation of the Quran, the Islamic holy book, to the Prophet Muhammad. Mubarak called for a religious discourse that "revokes terrorism and extremism." His language appeared chosen as a response to anti-Christian rioting by Muslims Alexandria, Egypt's second largest city a week ago. Four people were killed and 99 injured.