THE Pope has urged Egypt's leading imams to teach their students to reject violence in God's name and preach messages of peace and tolerance instead.

Francis spoke out during a delicate visit to the Arab world's most populous country after a spate of deadly Islamic militant attacks against Christians.

He 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 – not the armoured "pope-mobiles" of his predecessors.

His first event was a landmark visit to Cairo's Al-Azhar university, the revered 1000-year-old seat of Sunni Islam learning that trains clerics and scholars from around the world.

He warmly embraced Sheikh Ahmed el-Tayeb, Al-Azhar's grand imam who hosted the Pope and other senior Muslim and Christian leaders at a peace conference.

Speaking to the crowd, Francis recalled that Egypt's ancient civilizations valued the quest for knowledge and open-minded education, and that a similar commitment is required today to combat the "barbarity" of religious extremism among the young.

While Al-Azhar has strongly condemned Islamic fundamentalism, Egypt's pro-government media has accused its leadership of failing to do enough to reform the religious discourse in Islam and purge canonical books of outdated teachings and hatred for non-Muslims.

"As religious leaders, we are called to unmask violence that masquerades as purported sanctity," Francis said to applause from the crowd. "Let us say once more a firm and clear 'no' to every form of violence, vengeance and hatred carried out in the name of religion or in the name of God.

"To counter effectively the barbarity of those who foment hatred with violence, we need to accompany young people, helping them on the path to maturity and teaching them to respond to the incendiary logic of evil by patiently working for the growth of goodness."

Sheikh el-Tayeb thanked Francis for what he called his "fair" comments against charges of terror and violence levelled against Muslims and Islam.

"We need to cleanse religions from wrong notions, false piety and fraudulent implementations which stoke conflicts and incite hatred and violence," he said. "Islam is not a religion of terrorism because a minority from among its followers hijacked some of its texts" to shed blood and be provided by some with weapons and funds, he said to applause.

Francis has said he wanted to take a message of peace to a country that has for years endured an increasingly emboldened insurgency led by a local affiliate of the extremist Daesh group.

The two-day visit is also meant to lift the spirits of Egypt's large Christian community after three suicide bombings since December – including deadly twin Palm Sunday church attacks – killed at least 75 people. Egypt's Daesh affiliate claimed the attacks.

President Abdel-Fattah El-Sissi declared a nationwide state of emergency after the Palm Sunday attacks in a bid to better deal with the insurgency through wider police powers and swift trials.

The visit to Al-Azhar marked a diplomatic breakthrough for the Vatican after Sheikh el-Tayeb severed relations with Rome in 2011, after Pope Benedict XVI demanded Egypt better protect its Christian minority following a New Year's Eve church bombing that killed more than 20 people.