Pope Francis says one of the refugees he met on the Greek island of Lesbos was the Muslim widower of a Syrian Christian woman killed by extremists for refusing to renounce her faith.

Francis told the faithful in St. Peter's Square on Sunday that "she is a martyr."

Departing from his prepared remarks, Francis shared his experiences of the day earlier with thousands of people gathered for his blessing. He says among the 300 refugees he greeted Saturday on Lesbos was a Syrian widower with two children.

The pope said: "He is Muslim, and he told me that he married a Christian girl. They loved each other and respected each other. But unfortunately the young woman's throat was slashed by terrorists because she didn't want to deny Christ and abandon her faith."