Pope Francis has urged leaders to work together to fight the "plague of terrorism", saying in his New Year's address that a bloodstain was covering the world as it started 2017.
Speaking to some 50,000 people in St. Peter's Square for his traditional noon address, Francis departed from his prepared text to condemn the Istanbul nightclub attack that killed at least 39 people.
"Unfortunately, violence has stricken even in this night of good wishes and hope. Pained, I express my closeness to the Turkish people. I pray for the many victims and for the wounded and for the entire nation in mourning," he said.
"I ask the Lord to sustain all men of good will to courageously roll up their sleeves to confront the plague of terrorism and this stain of blood that is covering the world with a shadow of fear and a sense of loss," he said.
He said 2017 will be what people make of it.
"The year will be good in the measure that each one of us, with the help of God, seeks to do good day after day," he told the crowd on a cold morning.
Speaking on the day the 1.2 billion-member Roman Catholic Church marks its World Day of Peace, he said peace was constructed by saying 'no' to hate and violence and 'yes' to brotherhood and reconciliation.
Francis earlier said Mass in St. Peter's Basilica, where in a homily he said the lack of physical contact among people brought on by modern means of virtual communication "is cauterising our hearts and making us lose the capacity for tenderness and wonder, for pity and compassion."
