A record number of refugee and migrant children are traveling solo to escape violence and poverty, falling prey to abuse and human traffickers in their journey to a new life, the United Nations children’s agency said on Wednesday.

Be it to escape war in Syria or gang violence in Central America, natural disaster or famine, increasing numbers of children are on the move and are traveling alone, UNICEF said in a report.

About 200,000 unaccompanied children applied for asylum across 80 countries from 2015 to 2016 and another 100,000 children were stopped at the U.S.-Mexico border, UNICEF said.

Taken together, 300,000 children traveled alone worldwide from 2015 to 2016 - a five-fold increase since 2010, when 66,000 children were reported to be on the move, UNICEF said.

“Ruthless smugglers and traffickers are exploiting their vulnerability for personal gain, helping children to cross borders, only to sell them into slavery and forced prostitution,” Justin Forsyth,UNICEF deputy executive director, said in a statement.

“It is unconscionable that we are not adequately defending children from these predators.”

UNICEF said the central Mediterranean route between north Africa and Italy is one of the world’s deadliest, with 4,579 deaths last year, including some 700 children, many from Eritrea, Gambia, Nigeria, Egypt and Guinea.

Unaccompanied and separated children accounted for 92 percent of all children arriving in Italy by sea last year.

While the Mediterranean route is favored by traffickers - some children have even had organs removed - traffickers are also active on other routes, the report said.

Boys and girls account for three in every five victims of human trafficking in Central America and the Caribbean, according to the United Nations Office on Drugs and Crime.

Many of them face likely sexual exploitation, said Maria Cristina Perceval, UNICEF’s Latin America regional director.

“Because the difference with this and other crimes and exploitation is that a girl who is exploited sexually is seen as merchandise that can be used again and again,” Perceval told the Thomson Reuters Foundation in a phone interview.

Most children from Central America migrate to escape gang violence and poverty, or to join relatives living abroad.

UNICEF said human smugglers who guide children along their journey use rape, violence and extortion en route.

One migrant, 17-year-old Mary from Nigeria, was trapped in Libya for more than three months where she was raped by her smuggler as she tried to reach Italy, UNICEF said.

“He said to me, if I didn’t sleep with him, he would not bring me to Europe. He raped me,” Mary, who traveled alone, is quoted as saying.

Some smugglers operate a ‘pay as you go’ deal — asking for no money up front, but later demanding sums children may not be able to pay. They are then put to work to pay off the debt, through forced labor and prostitution, the report said.

One migrant, 16-year-old Aimamo, said he and his twin brother were forced to work on a farm in Libya for two months to pay their smugglers.

“If you try to run they shoot you and you die. If you stop working, they beat you,” Aimamo is quoted as saying in the report. “After working, they lock you inside.” (Reporting by Anastasia Moloney @anastasiabogota, Editing by Lyndsay Griffiths. Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women’s rights, trafficking, property rights, climate change and resilience. Visit http://news.trust.org)