Asad Ullah, a 10-year-old migrant from Afghanistan, spent weeks travelling in the cold and rain after his father sent him off to look for a brighter future in Europe.

Ullah told The Associated Press on Thursday that he set off in a group of migrants with smugglers through Iran, Turkey and Bulgaria before reaching Serbia nearly two months ago. During his journey, Ullah slept out in the open and lived in makeshift migrant shelters with little food and no facilities. He kept close to other migrants, afraid not to get lost.

"It is very hard, but I am going to Europe," said Ullah, who was among more than 100 minors brought last week to a center for asylum-seekers on the outskirts of the Serbian capital, Belgrade.

Previously, he had spent weeks in a now-demolished migrant shelter in the city center. He said his father sent him away to Europe rather than stay in Afghanistan where "there is no life."

"He (his father) said to go to Europe for American life," Ullah said in broken English. "I said: 'OK, I go to Europe.'"

A report by the U.N. children's agency published on Wednesday warned that more than 300,000 children like Ullah have been migrating alone worldwide over a two-year period, in a dramatic escalation of a trend that has forced many young refugees into slavery and prostitution.

The numbers of refugee children have grown in Serbia too, where about 7,000 refugees and migrants have been stranded, unable to cross the heavily guarded borders of neighboring EU countries Hungary and Croatia. Michel Saint-Lot, the UNICEF representative in Serbia, said that around 3,200, or 46 percent, of all refugees and migrants in Serbia are children, while every third child is unaccompanied.

"That is one too many," he said.

Saint-Lot added that while on the road on their own, unaccompanied children are exposed to abuse and violence and face "potential issue of being trafficked, for sexual exploitation, for slavery and lack of access to basic care."

"Those are major challenges for the children," Saint-Lot insisted.

While some minors set off with their families, they end up separated either by chance, or by smugglers who often split up families as a way to control them. Some, like Ullah, are sent away from home by parents who want them to reach Western Europe so they eventually can bring the rest of the family over, or earn money to support relatives who stayed behind.

Saint-Lot said that the fact that they are stranded in Serbia, unable to move on to their desired destinations in Europe, has put additional strain on the children — leading to psychological pressure and breakdowns in some cases.

"The most important aspect is ensuring that all children have access to learning, that they are protected from abuse, neglect, sexual exploitation, that there is proper psychological care," Saint-Lot said.

Insah Ullah from Afghanistan, who is 17 and isn't related to Asad Ullah, was also brought from Belgrade city center to the camp in the suburb of Krnjaca last week.

On Thursday, he and other migrants could be seen playing in the camp yard on a sunny day. Insah Ullah said he would never have left his home if he had hope for a future in Afghanistan.

"I miss my family and I love my family too much and I miss my country," he said. "No one wants to leave his country, no one wants to leave their parents, because if parents are with you, everything is with you."

"If they are not, nothing is with you" Ullah said.


Jovana Gec contributed to this report.