VATICAN CITY (AFP) - Pope Francis offered a Christmas message on Friday (Dec 25) of mitigated hope for an end to the world's conflicts, backing recent accords on Syria and Libya and praising those who shelter migrants.

"We pray... that the agreement reached in the United Nations may succeed in halting as quickly as possible the clash of arms in Syria," he said, while urging that "the agreement on Libya be supported by all".

Delivering his Christmas message from the balcony of St Peter's Basilica, the 79-year-old pontiff touched on several other conflict zones, including Iraq, Yemen, the DR Congo, Burundi and South Sudan following a year of violence and suffering that forced hundreds of thousands to flee their homes.

The Pope, addressing tens of thousands of pilgrims in the sunny square, also decried "brutal acts of terrorism, particularly the recent massacres which took place in Egyptian airspace, in Beirut, Paris, Bamako and Tunis".

After a year that saw more than one million migrants reach Europe, Francis praised those who shelter them, asking God to "repay all those, both individuals and states, who generously work to provide assistance and welcome" to them.

The leader of the world's 1.2 billion Catholics also used the traditional Urbi et Orbi address to denounce the destruction of cultural heritage.

In a clear reference to the Islamic State in Iraq and Syria group (ISIS), he said their "atrocities... do not even spare the historical and cultural patrimony of entire peoples". ISIS has launched a campaign of destruction against buildings and monuments that fall outside its harsh interpretation of Islam, ranging from Christian churches to Muslim graves, as well as ancient treasures like the temples of Palmyra.