Pope Benedict has denounced as “absurd” a string of Christmas day bombings in Nigeria, including one that killed 35 people at a Roman Catholic church.

Speaking on Monday from his window overlooking St. Peter's square, the Pope said he learned with profound sadness about the attacks, and invited people to pray for the victims. At least 39 people were killed overall.

The radical Muslim sect Boko Haram has claimed responsibility for the apparently coordinated attacks. It is the second consecutive year the group has targeted places of worship on Christmas day.

The bomb attacks took place at a Catholic church near Abuja, an evangelical church in the central city of Jos and a church in the northeastern town of Gadaka. A fourth attack took place in the Yobe state capital of Damaturu, where a car bomb exploded near the secret police headquarters.

The violence drew international condemnation.

Nigeria has struggled with a wave of violence centered in the country's north, where government security forces are battling Boko Haram.

The group has said it wants to establish a strict Islamic state in northern Nigeria and does not recognize the government or the country's constitution.

The country of 150 million is about evenly divided between Muslims, who mostly live in the north, and Christians who dominate in the south.

Hundreds of others have died this year in bombings and shootings blamed on Boko Haram.