Anis, 4, from Syria (C) is bathed by his mother, as others wash their clothes and shoes, at the Souda municipality-run camp for refugees and migrants on the island of Chios, Greece. REUTERS/Alkis Konstantinidis Thousands of unaccompanied child refugees have been coming to Europe in recent months and authorities are struggling to find a way to care for them.

In Greece, the situation has gotten so bad that the police regularly lock them up in overcrowded cells in unsanitary conditions for weeks at a time, a new report by Human Rights Watch claims.

Children are sometimes held with adults that are not related to them and in deplorable hygienic conditions:

"In some cases, they were made to live and sleep in overcrowded, filthy, bug- and vermin-infested cells, sometimes without mattresses, and were deprived of appropriate sanitation, hygiene, and privacy."

The children also have next to no access to counselling or legal aid while detained, no interpreter in order to communicate with the police and, with the exception of one facility, no access to books or games.

Greece's chronic shortage of accommodation for the refugees is now breaking international and Greek law by detaining the children, according to the HRW report. Greek authorities are aware of the problem but do very little to remedy the situation, it adds.

The country, itself facing dire austerity measures and an ongoing financial crisis, is trying to manage huge numbers of refugees with little help from Europe. Over 2,000 Greek sea rescue volunteers, have also won the annual Nansen prize, an award recognising outstanding service to the cause of refugees, the UN refugee agency announced Tuesday.

But with almost 165,000 people reaching Greek shores since January, Greece is the country receiving the most refugees out of the whole European Union. And in 2016, almost a third of the refugees getting to Europe were children, according to the United Nations Refugee Agency.

A broken doll is left on a plastic chair at the Souda municipality-run camp for refugees and migrants, on the island of Chios, Greece, September 7, 2016. REUTERS/Alkis Konstantinidis Since January, Greek police detained 161 children, according to the report, and they are often detained longer than is allowed under the Greek law's already high ceiling of 45 days.

One 15-year-old Algerian boy told HRW that he couldn't sleep because he was scared of the adults in the cell with him: "I could not feel safe, because the other people [in the cell] were doing drugs… When they were fighting, of course I was scared and I couldn't sleep."

HRW interviewed 42 children for the report and visited police stations and detention centres where they were held.

With some 28 million children who have been driven from their homes by conflict around the world, the problem is hardly confined to Greece. In Europe alone, another crisis point for children is the Jungle migrant camp in Calais, northern France, where an estimated 800 unaccompanied minors are desperately trying to reach the UK.