Pope Francis held an emotional meeting with hundreds of children on Saturday, including a Nigerian boy whose parents drowned in a shipwreck, and told them migrants “are not dangerous, but in danger”.

The meeting followed a surge in migrant traffic this week between Libya and Italy, with more than 14,000 saved from overcrowded boats since Monday and three consecutive days of shipwrecks in which hundreds may have died.

Three infants were among 45 bodies recovered at sea on Friday, UNICEF Italy said.

Meeting the mostly Italian children who took a special train from southern Italy to the Vatican’s own railway station, Francis hugged the Nigerian boy, Osayande, who has been taken in by an Italian family.

He showed them an orange life jacket he was given by a Spanish rescuer working to save lives in the Mediterranean.

“He brought me this life jacket and, crying a little bit, he said: ‘Father, I failed. There was a little girl in the sea and I wasn’t able to save her. All I could reach was her life jacket'” the pope said.

“What was her name? I don’t know – a little girl without a name … She’s in heaven and watching us. Let’s close our eyes, think about her and give her a name.”

The influx of migrants and refugees into Europe in recent years has fanned popular fears of foreigners and prompted politicians to tighten border controls and limit the number of newcomers allowed to stay.

The pope has repeatedly sought to underscore the plight of these people, especially the hundreds of thousands who have risked their lives to come to Europe in flimsy boats.

He visited the Greek island of Lesbos last month, bringing 12 refugees back on his plane to set an example of how other people and countries should welcome refugees.

In southern Italy on Saturday, about 4,000 migrants made it to dry land, many of them exhausted and dehydrated.

“The number of minors who make the journey on their own and arrive in Europe is much higher than what we saw last year,” Save the Children spokeswoman Giovanna Di Benedetto said.

“But we are increasingly coming across much younger children, children of nine or ten years of age, who have made the journey alone or who have lost their parents or family members with whom they were travelling,” she said.