Pope Francis is visiting Egypt on a visit aimed at improving Christian-Muslim dialogue, three weeks after bombings at two Coptic churches killed 45 people and he has delivered a strong peace message at a key center for Islamic learning.

He was greeted by President Abdel Fattah al-Sisi at his palace in Cairo on April 28, and is also meeting Muslim and Christian leaders, The Associated Press reported.

Religious leaders must denounce violations of human rights and expose attempts to justify violence and hatred in the name of God said Francis' message at the International Peace Conference at the Al-Azhar conference center in Cairo.

The Pope's words came at the start of his two day trip to Egypt, following a courtesy visit to President Abdel-Fattah Al-Sisi.

The pontiff told reporters his trip would be a "journey of unity and fraternity," the BBC reported.

Security is high for the 27-hour visit, but Pope Francis is not using an armored car.

Later the 80-year-old head of the world's 1.3 billion Catholics visted al-Azhar University, a key center of Sunni Islamic learning where he attended the inter-faith and ecumenical peace conference.

"Egypt lifted the lamp of knowledge, giving birth to an inestimable cultural heritage, made up of wisdom and ingenuity, mathematical and astronomical discoveries, and remarkable forms of architecture and figurative art.

"The quest for knowledge and the value placed on education were the result of conscious decisions on the part of the ancient inhabitants of this land, and were to bear much fruit for the future," said Francis in his address.

Before the visit - the first papal trip to Cairo in 20 years - he said he was travelling as a "messenger of peace".

It comes as Egypt's Coptic Christians - who make up 10 percent of the country's mainly Muslim population - face increased threats. The majority of the Copts are Orthodox, with less than 150,000 of them who are Catholic.

Speaking at the same conference as Pope Francis the Eucmenical Patriarch Bartholomew, considered by many to be the spiritual head of Eastern Orthodox Christians, said protecting human freedom and dignity is a vital contribution to peace-building by religious communities.

"During the last two decades, humanity has experienced continuous terrorist attacks, which are the cause of death and hurt of thousands of people, and which are becoming the greatest threat and source of fear for contemporary societies," he said.

"Since then, religions have been often suspected or openly accused for inspiring terrorism and violence."

Religion is a vital factor in the peace process, Bartholomew said. "Religion can, of course, divide by causing intolerance and violence. But this is rather its failure, not its essence, which is the protection of human dignity."

Interreligious dialogue recognizes the differences of religious traditions and promotes peaceful coexistence and cooperation between people and cultures, he continued. "Interreligious dialogue does not mean to deny one's own faith, but rather to change one's mind or attitude towards the other."

In a common declaration, signed by Pope Francis and Coptic Pope Tawadros II, Catholics and Copts declared for the first time that they will recognize each other's sacrament of baptism.