Updated

The Latest on Europe's migration crisis (all times local):

4:10 p.m.

Turkey has denied reports Turkish border guards have shot at Syrian civilians fleeing the Islamic State group.

Foreign Ministry spokesman Tanju Bilgic said Sunday that such claims "are irrelevant to reality."

Human Rights Watch has urged Turkey to allow in thousands of Syrians fleeing clashes between rebels and IS in northern Syria.

The advocacy group quoted a Syrian refugee who said Turkish border guards shot at hundreds of people approaching a border wall.

Turkey, which borders Syria and hosts roughly 2.7 million Syrian refugees, has tightened border restrictions in the past year.

Aid agencies, Bilgic said, are taking "necessary precautions on both sides" of the border to help Syrians displaced in the latest fighting.

Turkey is reportedly building three container cities with the capacity to house about 40,000 Syrians.

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2:15 p.m.

Greek authorities, worried about the spread of diseases in makeshift refugee camps, are urging migrants to relocate to organized camps with better living conditions.

A flyer is circulating at the Idomeni migrant camp on Greece's border with Macedonia, saying that gastroenteritis, lice and scabies are spreading among the almost 10,400 people there. Written in four languages, including Arab and Farsi, it urges the migrants to relocate to one of several organized camps across Greece.

But the migrants and refugees who have been stranded at Idomeni ever since Austria and several Balkan countries shut down their borders to them in mid-March are reluctant to leave. On Saturday, departing migrants filled just one bus.

In addition to Idomeni, another 10,000 migrants are staying in makeshift camps in mainland Greece.

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1:25 p.m.

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."