A member of the Italian Red Cross holds a child after disembarking from the Italian Navy vessel Aviere in the Sicilian harbour of Augusta, Italy, June 10, 2016. REUTERS/Antonio Parrinello

LONDON (Thomson Reuters Foundation) - The number of lone migrant children arriving in Italy by boat more than doubled in 2016 from the previous year, an “alarming trend” that leaves thousands of young people at risk of abuse, the United Nations children’s agency said on Friday.

Around 25,800 unaccompanied children crossed the Mediterranean to reach Italy in 2016, UNICEF said, with the majority originating from Eritrea, Egypt, Gambia and Nigeria.

While most were teenaged boys, the agency said a growing number of girls were also making the perilous sea journey and were at risk of sexual exploitation.

“These figures indicate an alarming trend of an increasing number of highly vulnerable children risking their lives to get to Europe,” said Lucio Melandri, UNICEF’s emergency manager.

“Current systems in place are failing to protect these children who find themselves alone in a totally unfamiliar environment. Because they are on the move, a coordinated European response is needed to keep them safe.”

Last year a record 181,000 boat migrants, mostly from Africa, reached Italy. The majority paid Libyan people traffickers to make the journey.

The Missing Migrants Project, set up by the U.N.’s International Organization for Migration, has recorded 11 migrants deaths in the Mediterranean since the start of the year, including four who died of hypothermia at Europe’s land borders with Turkey.

The EU all but halted a migrant influx into Greece through a deal last year with Turkey to hold back Syrian refugees. But doing the same in Italy’s case is more problematic because of the lack of effective state authority in Libya.