Pope Francis has urged Egypt's leading imams on Friday to teach their students to reject violence in God's name and preach messages of peace and tolerance instead, forging ahead with a delicate visit to the Arab world's most populous country following a spate of deadly Islamic militant attacks against Christians.

Francis arrived to a subdued welcome and a heavy police presence at Cairo's international airport. But he brushed off security concerns by driving into town with his windows rolled down in a simple blue Fiat rather than an armoured vehicle.