Pope Francis delivered a plea for peace in his first Easter Sunday message to the world, decrying seemingly endless conflict in the Middle East, Africa and the Korean peninsula.

In his first celebrating Mass on the most important day in the Church's calendar, he prayed along with more than 250,000 people in flower-bedecked St Peter's Square.

Francis shared in his flock's exuberance as the crowd celebrated Christianity's core belief that Jesus Christ rose from the dead following crucifixion.

After Mass, he stepped aboard the Popemobile for a cheerful spin through the joyous crowd, kissing babies and patting children on the head.

One admirer of both the Pope and of his favourite football team, Argentina's Saints of San Lorenzo, insisted Francis take a team jersey he was waving at the pontiff. A delighted Francis obliged, briefly holding up the shirt, and the crowd roared in approval.

Francis has repeatedly put concern for the poor and suffering at the centre of his messages, and pursued his promotion of the causes of peace and social justice in the Easter speech delivered from the central balcony of St Peter's Basilica, from which he was introduced to the world as the first Latin American Pope on March 13, shortly after his election.

He said he was joyfully aiming his Easter greetings, at "every house and every family, especially where the suffering is greatest, in hospitals, in prisons".

Francis prayed Jesus would inspire people to "change hatred into love, vengeance into forgiveness, war into peace".

In his softly and slowly-pronounced speech, Francis defined Easter as an "exodus, the passage of human beings from slavery to sin and evil to the freedom of love and goodness".

As popes before him have, he urged Israelis and Palestinians, who "struggle to find the road of agreement" to find the courage to resume peace talks and end a conflict that "has lasted all too long".

And, in reflecting on the two-year-old Syrian crisis, Francis asked: "How much suffering must there still be before a political solution can be found?"

The Pope also expressed the desire for a spirit of reconciliation on the Korean peninsula, where North Korea says it has entered a state of war with South Korea.

He also decried violence in Africa, where he singled out for condemnation terrorists' hostage-taking, as well as strife in Mali and warfare in the Democratic Republic of Congo and in the Central African Republic, which have driven people from their homes.

The first pontiff to come from the Jesuits, an order with special concern for the poor, and the first Pope to name himself after St Francis, a medieval figure who renounced wealth to preach to the down-and-out, Francis lamented that the world is "still divided by greed looking for easy gain, wounded by the selfishness which threats human life and the family, selfishness that continues in human trafficking, the most extensive form of slavery in this 21st century".

Earlier, Francis celebrated Mass on the esplanade in front of the basilica. He frequently bowed his head as if in silent reflection.

While Francis has just begun to make his mark on the Church, he has made it plain he has no desire to embrace much of the pomp customarily associated with the office, declining ornate outfits and only accepting a red stole when it was time to give the crowd his solemn blessing.