VATICAN CITY — Pope Benedict XVI appealed for peace in the world's troublespots in his Easter Sunday message but one of the holiest days for Christians was marred by fresh violence in Nigeria and Syria.

At least 20 people were killed in northern Nigeria in a car bombing outside a church, the latest in a wave of attacks against the Christian community in Africa's most populous country that have been blamed on an Islamist sect.

Speaking before a crowd of 100,000 faithful in St Peter's square in Rome, the pope called for an end to the bloodshed in Syria where fighting continues to claim lives ahead of a deadline next week for all sides to cease fire.

"Particularly in Syria, may there be an end to bloodshed and an immediate commitment to the path of respect, dialogue and reconciliation, as called for by the international community," he said.

The pontiff also voiced hope that the thousands of refugees fleeing the crisis were given help relieve "their dreadful sufferings".

Turning to Iraq, he encouraged the people to "spare no effort in pursuing the path of stability and development" and in the Holy Land, he urged Israel and the Palestinians to "courageously take up anew the peace process," with direct talks between the two sides frozen since September 2010

UN peace envoy Kofi Annan declared himself shocked by the "unacceptable" uescalation of violence in Syria, where 130 people were killed Saturday in one of the bloodiest days since protests against President Bashar al-Assad's regime erupted in March last year.

At least 11 more people were killed on Sunday as Assad's regime insisted it would not pull out from cities in Syria as called for by the UN Security Council unless there were written guarantees from rebels.

Pope Benedict also called for peace and stability to return to Mali after a military coup last month which was followed by a widescale offensive by Tuareg rebels and armed Islamist extremists who overran much of the northeast.

Benedict also condemned the "savage terrorist attacks" on Christian churches in Nigeria, as a car bomb exploded outside a church in the city of Kaduna just as Easter services were being held inside.

"To Nigeria, which in recent times has experienced savage terrorist attacks, may the joy of Easter grant the strength needed to take up anew the building of a society which is peaceful and respectful of the religious freedom of its citizens," the pope said.

One rescue official said at least 20 people were killed in the bombing, which was similar to attacks carried out on Christmas Day against churches in northern Nigeria which were claimed by Boko Haram.

In his Easter message, the pope also urged reconciliation in the Great Lakes Region of Africa, and in Sudan and South Sudan, where deadly border violence has erupted, raising fears of all-out war between the rival neighbours.

The Latin Patriarch of Jerusalem, Fuad Twal, spoke of the fear of Christians in the Middle East faced by a rise of extremist Islam.

"I wish all of you a beautiful and holy feast of the Resurrection, in the knowledge that the events unfolding in the Middle East threaten our region, our people and our Christians, that add a sombreness to this Easter joy," he said.

Many, he said, "live in fear: fear due to the unrest in our region; fear of an uncertain, even dark future," Twal, the most senior Roman Catholic in the Middle East, said in a homily delivered at the Church of the Holy Sepulchre in Jerusalem's Old City.

Easter celebrations around the world also saw Catholic fanatics in the Philippines nailing themselves to crosses in a bloody display of religious frenzy, while in Cuba, which the pope visited last month, state-run television broadcast a Good Friday ceremony for the first time in more than 50 years.

In Caracas, President Hugo Chavez made an emotional plea that put his health and political future in the spotlight, begging God "don't take me yet" at an Easter mass on Maundy Thursday.