At least the 10.000 refugee children without parental or guardian escorts disappeared after arriving in Europe, the British Guardian quoted Sunday as saying, referring to Europol, the European police and intelligence agency of the European Union trying to determine the extent of one of the most difficult aspects of the migration crisis.

Brian Donald, one of Europol's chief, said thousands of vulnerable children disappeared after they were registered in state offices, stating that only in 5000 children was missing in Italy, while still fails to know about 1000 children in Sweden. He warns that refugees and migrants are now in the midst of a highly sophisticated pan-European "criminal infrastructure".

"It is not unreasonable to say that we are talking about the least 10.000 children. They will not all be exploited by criminal organizations, maybe some are passed on to members of the wider family, but we just do not know where they are, what they are doing and who they are, "Donald said.

According to the data of the "Save the Children" association, it is estimated that last year, 26.000 males escorted to Europe without escort. According to the available data, Europol believes that the millions of people who entered Europe last year, 27 as minors.

"Whether they are registered or not, we are talking about 270.000 children. Not all of them have entered without parents, but we have evidence that a large number of them entered without escort, "Donald said, pointing out that 10.000 was in fact a modest estimate.

In October, officials of the Swedish port city of Trelleborg announced that around 1000 refugee children without parents who arrived in that city a month ago vanished missing and that after their disappearance there was very little information.

"Juvenile offenders coming from areas affected by conflicts are far the most vulnerable group; these are the ones who have just sent their families to Europe to come to them or they are about minors who fled with other family members, "says Marijana Berket of the Organization for Security and Co-operation in Europe (OSCE).

Donald has confirmed that Europol has evidence showing that some refugee children without parental escorts have ended up as sex slaves.

"Crime infrastructure has evolved over the past 18 months in order to benefit from migration inflows. In Germany and Hungary, prisons were opened in which the vast majority of those arrested ended for criminal offenses related to the migration crisis, "Donald said.

Europol notes a very disturbing phenomenon where organized gangs smuggling migrants into the EU are then transformed into criminal associations for smuggling human beings for sexual exploitation and enslavement. Particularly, Donald adds, worried countries, so-called. Balkan routes that meet with a huge number of migrant children who are not accompanied by their parents and are seeking help because they face it daily.

Donald calls on the public to watch and keep their eyes wide open as most of our missing children are almost in front of us.

"These kids are in the community. If they are abused it happens in the community. They are not hidden in the woods, though they probably are, but are mostly in the community and are visible. As citizens, we have to be warned, "Donald said.

The EU's chaotic approach to the migrant crisis has resulted in last week's calls to expel Greece from the Schengen area, and this development of the situation is a high UN official said that the Union's position on an aggressive crisis fell to a "new lowest point."

"Such a move Greece would literally turn into a fenced open space for thousands of asylum seekers. The idea is inhumane and represents a serious violation of fundamental European principles, "UN Special Representative for Migration Peter Sutherland said.