Greg Maravas and Nikolia Apostolou

Special to USA TODAY

LESBOS, Greece — In an emotional visit to a fenced-in refugee center on this Greek island, Pope Francis told hundreds of displaced families Saturday that "you are not alone" — and underscored his message by taking three families of Syrian Muslim refugees back to Rome with him.

The 12 refugees, including six children, joined the pope on his plane after a five-hour visit to the Moria detention center. The pope also asked European leaders to do more to help the thousands of refugees stuck in camps.

"Refugees are not numbers; they are people who have faces, names, stories and need to be treated as such," Francis tweeted at one point on Saturday.

Two of the families are from Damascus, and one is from an area of Syria now occupied by the Islamic State, according to a statement by the Vatican press office.

Asked why all the families were Muslims, the pope told reporters on his return flight to Rome that the choice was not between Christians and Muslims and that those who were selected all had their papers in order. The Vatican said the details were worked out in an agreement between the Greek and Italian authorities.

“I have always said that building walls is not a solution. We saw walls during the last century and they did not resolve anything. We must build bridges. Bridges are built with intelligence, with dialogue, with integration,” he said, according to an official Vatican transcript.

Asked whether Europe can open its arms to all the misery in the world, the pope noted the impact of war and hunger — and how the factions fighting in Syria have been armed by others. “I would invite the producers of arms to spend a day in the camp (in Lesbos)," he said. "I believe that would be good."

The 12 refugees will be cared for in Rome by the Community of Sant'Egidio, a Catholic lay organization dedicated to charity, the Vatican said. The Vatican is already hosting two refugee families in Rome.

Nour Essa, 30, a Palestinian-Syrian scientist, is one of the 12 who returned to Rome with the pope. She will be relocated along with her 3-year-old son and husband. The family fled because her husband was being pressured to join the Syrian army.

"We heard of the EU-Turkey deal which would be implemented on March 20 and decided despite the bad weather to get on one of the boats to Lesbos," she said. "We were very lucky: Friends of ours that were living with us in Turkey that came the next day were not given papers and are still in jail in Moria camp. Instead, we will be refugees in Italy!"

The pope's gesture came as the European Union begins to implements a controversial plan to deport refugees from Greece back to Turkey.

The deal stipulates anyone arriving clandestinely on Greek islands on or after March 20 will be returned to Turkey unless they successfully apply for asylum in Greece. For every Syrian sent back, the EU will take another Syrian directly from Turkey for resettlement in Europe.

In return, Turkey was granted concessions including billions of dollars to deal with the more than 2.7 million Syrian refugees living there, and a speeding up of its stalled accession talks with the EU.

Human rights groups have denounced the deal as an abdication of Europe's obligations to grant protection to asylum-seekers.

Hours before Francis arrived, the European border patrol agency Frontex intercepted a dinghy carrying 41 Syrians and Iraqis off the coast of Lesbos. The refugees were detained and brought to shore in the main port of Mytilene, the Associated Press reports.

When the pope visited 250 refugees at the Moria detention center, one young girl fell sobbing to her knees in front of him. The pontiff gently lifted her to her feet and stroked her hair. A woman told the pope that her husband was in Germany, but that she was stuck with her two sons in Lesbos.

The pope made the rounds among many of the refugees, shaking hands with young people along a fence and later addressing the group.

"I want to tell you that you are not alone," he said. "In these weeks and months, you have endured much suffering in your search for a better life. Many of you felt forced to flee situations of conflict and persecution for the sake, above all, of your children, your little ones."

Francis was met at the airport by Greek Prime Minister Alexis Tsipras along with Patriarch Bartholomew, spiritual leader of the world's Orthodox Christians, and the Archbishop of Athens.

Francis thanked Tsipras for the "generosity" shown by the Greek people in welcoming foreigners despite their economic troubles and called for a response to the migration crisis that respects European and international law, the Vatican said.

Tsipras said he was proud of Greece's response "at a time when some of our partners — even in the name of Christian Europe — were erecting walls and fences to prevent defenseless people from seeking a better life," according to the Associated Press.

The son of Italian immigrants to Argentina, Francis has made the plight of refugees, the poor and downtrodden the focus of his ministry as pope, denouncing the "globalization of indifference" that the world shows the less fortunate.

He visited the Italian island of Lampedusa in the summer of 2013, his first trip outside Rome as pope, after a dozen migrants died trying to reach the southern tip of Europe. He made a similar gesture more recently at the U.S.-Mexican border, laying a bouquet of flowers next to a large crucifix at the Ciudad Juarez border crossing in memory of migrants who died trying to reach the U.S.

While such visits have brought the controversial topic front and center, the Vatican insists Saturday's visit is purely humanitarian and religious in nature, not political or a "direct" criticism of the EU plan.

But Vatican spokesman Federico Lombardi told reporters Francis' position on Europe's "moral obligation" to welcome refugees is well-known, and that the EU-Turkey deportation deal certainly has "consequences on the situation of the people involved."

The Vatican official in charge of migrants, Cardinal Antonio Maria Veglio, was even more explicit, saying the EU-Turkey plan essentially treats migrants as merchandise that can be traded back and forth and doesn't recognize their inherent dignity as human beings.

"He is slightly provocative," said George Demacopoulos, chair of Orthodox Christian studies at the Jesuit-run Fordham University in New York. Citing Francis' Mexico border visit in February, in the heat of a U.S. presidential campaign where illegal immigration took center stage, he added: "He is within his purview to do so, but that was a provocative move."

"Refugees and migrants in Lesbos are like an exhibit,” said Stratis Pallis, 26, a psychotherapist who has been working with migrants in the camps on the island. "Everyone comes to see them, the famous and the ordinary. These visits help neither the refugees nor the visitors, as the situation doesn't change."

Travel agent Maria Androulaki said, however, the pontiff’s trip bore a message of compassion that was fitting for an island that has been the transit hub in the past year for almost 1 million migrants fleeing the Middle East and North Africa in search of peace and jobs in Europe. Thousands died in the crossing. Many were buried in the island’s soil.

"I don't see anything negative in the pope's visit,” Androulaki said. “All the world's eyes will be on Lesbos. Millions of people will learn about Lesbos and the island will be televised throughout the world. The refugee crisis taught us to be more humane."

The three religious leaders had lunch with a group of the detainees at the Moria camp, formerly a housing center for refugees but one now turned into a detention center. Its residents are barred from leaving the facility as officials process their asylum applications.

“At Moria detention camp on Lesbos, we witnessed with our own eyes the crushing impact the EU-Turkey deal is having on men, women and children, including a large number of vulnerable refugees, being held arbitrarily," said Gauri van Gulik, deputy director for Europe at Amnesty International. "The pope should make clear that the failure to change course would be Europe’s shame.”