VATICAN CITY: Pope Benedict called for an end to violence in Syria and a resumption of Middle East peace talks on Sunday on a Christmas Day marred by a bomb blast at a Catholic Church in Nigeria.

The leader of the world's 1.3 billion Roman Catholics delivered his twice-yearly "Urbi et Orbi" (to the city and the world) message and blessing to tens of thousands of people in St Peter's Square on a crisp but clear day as millions of others watched on television around the world.

At the end of his address, the 84-year-old pope, celebrating the seventh Christmas season of his pontificate, delivered Christmas greetings in 65 languages, including Turkish, Hebrew, Arabic, Swahili, Hindi, Urdu and Chinese.

"May the Lord come to the aid of our world torn by so many conflicts which even today stain the earth with blood," he said, speaking in Italian from the central balcony of St Peter's Basilica.

"May the Prince of Peace grant peace and stability to that Land where he chose to come into the world, and encourage the resumption of dialogue between Israelis and Palestinians. May he bring an end to the violence in Syria, where so much blood has already been shed," he said in a firm, steady voice.

At least 5,000 people have been killed in nine months of violence that has rocked the Arab nation in clashes between government forces and protesters calling for the ouster of President Bashar al-Assad.

Declaring "let us speak out for those who have no voice," Benedict also called for more help for those suffering from hunger, food shortages and displacement in the Horn of Africa, and for those affected by floods in Thailand and the Philippines.

The pope did not mention a blast at a Catholic church on the outskirts of the Nigerian capital Abuja in his address, which was prepared before news of explosion arrived in Rome.

But Vatican spokesman Father Federico Lombardi condemned the blast as blind, absurd "terrorist violence" that enflames hate.

"We are close to the suffering of the Nigerian Church and the entire Nigerian people so tried by terrorist violence, even in these days that should be of joy and peace," Lombardi told Reuters.

According to early reports, at least 19 people were killed.

In his address he also called for full reconciliation and stability in Iraq and Afghanistan.

DECRIES COMMERCIALISATION OF CHRISTMAS

While his Christmas Day message took a partly political slant, mentioning some of the world's flash points, Benedict's Christmas Eve homily some 14 hours before lamented how the true meaning of the day had been overshadowed by materialism.

In that homily, he urged humanity to see through the superficial glitter and commercialism of the season and rediscover the real significance of the humble birth of Jesus.

"Today Christmas has become a commercial celebration, whose bright lights hide the mystery of God's humility, which in turn calls us to humility and simplicity," he said.

"Let us ask the Lord to help us see through the superficial glitter of this season, and to discover behind it the child in the stable in Bethlehem, so as to find true joy and true light."

"... let us strip away our fixation on what is material, on what can be measured and grasped. Let us allow ourselves to be made simple by the God who reveals himself to the simple of heart," he said.

Benedict urged his listeners at the Saturday night Mass to find peace in the symbol of the powerless Christ child in a world continually threatened by violence.

He also urged that those marking the holiday in poverty, suffering or far from home not be forgotten.

At the start of Saturday night's Christmas Eve service, he was wheeled up the central aisle of St Peter's Basilica standing on a mobile platform which he has been using since October.

The Vatican says it is to conserve his strength, allow more people to see him and guard against attacks such as one on Christmas Eve, 2009, when a woman lunged at him and knocked him to the ground. He is believed to suffer from arthritis in the legs.

But he seemed to be in good shape during the solemn service in Christendom's largest church as choirs sang, cantors chanted and music filled the centuries-old basilica.

The pope continues his Christmas and New Year's celebrations on Dec 31 with a year-end Mass of thanksgiving known by its Latin name Te Deum.

On January 1 he marks the Roman Catholic Church's World Day of Peace, on January 6 he marks the Epiphany and on January 8 will baptise several newborns in the Sistine Chapel.

He is due to visit Mexico and Cuba in March.