Pope Francis has paid a highly emotional visit to a migrant detention center in Greece, in a bold gesture of solidarity for the refugees whose influx has roiled European politics.
Migrants wept, pleaded for help, and threw themselves at his feet as Francis toured the facility on the small island of Lesbos, which has become the front line of a massive humanitarian crisis facing Europe.
They chanted "freedom, freedom" as the pope walked through the camp, where about 3,000 migrants are being held under a controversial deal between the European Union and Turkey.
"I want to tell you, you are not alone," he said. "As people of faith, we wish to join our voices to speak out on your behalf. Do not lose hope!"
The leader of the world's 1.2 billion Roman Catholics also urged Europe to treat migrants with dignity.
"We hope that the world will heed these scenes of tragic and indeed desperate need, and respond in a way worthy of our common humanity," he said in his speech, viewed by many as having strong political undertones.
Over the past year, hundreds of people fleeing war and poverty have died making the short but dangerous crossing from Turkey to the shores of Lesbos in inflatable boats. The island is full of unmarked graves.
"This is a trip marked by sadness," Francis told reporters during the flight from Rome, describing the migrant crisis as "the greatest humanitarian catastrophe since World War II."
The pontiff spent about six hours on the island together with Patriarch Bartholomew, spiritual leader of the world's Orthodox Christians, and Greek Archbishop Ieronymos.
During a brief meeting following his arrival at the airport, Francis thanked Greek Prime Minister Alexis Tsipras for the "generosity" shown by the Greek people in welcoming in foreigners despite their own economic troubles.
Tsipras told the pope that he was proud of his country's response at a time when some EU members "were erecting walls and fences to prevent defenseless people from seeking a better life."
Francis brought 12 refugees, including 6 children, back with him to Italy.
The Vatican confirmed that three Muslim families whose homes were destroyed in the conflict raging in Syria were travelling to Rome with the pope.
The Vatican will take responsibility for supporting the families.
The decision is not unprecedented, since the Vatican is already hosting two refugee families.
Aid organizations have described conditions at Moria, a disused army camp, as appalling.
The European Union struck an agreement last month to ensure that so-called economic migrants who travel to the Greek islands on boats operated by people smugglers are quickly sent back to Turkey.
Turkey has agreed to take them in return for billions in euros, a deal that has angered many rights activists.