“Children stranded without families should have proper shelter, care and protection, and there are solutions that could make this a reality for them,” said Laurent Chapuis, Country Coordinator for UNICEF's refugee and migrant response in Greece in a press release issued over the weekend.

The solutions include transfer these children to shelters on the mainland without delays, devote available funding to existing shelters with the right standards, and put more foster care or supervised living schemes in place, he added.

Although the Greek authorities and their partners have made tremendous efforts in responding to the needs of children and families, the recent surge in the refugee and migrant arrivals has led to further overcrowding and deteriorating living conditions in island camps, with some reception facilities hosting twice as many as they were designed for.

In September, there were more than 5,700 arrivals in Greece compared to an estimated 3,080 arrivals a year earlier.

There are now some 1,800 unaccompanied children waiting for a place in shelter, living in open sites, reception centres, or who are otherwise stranded on the islands or in de facto detention centres. Some of these children are even living on the streets, and the approaching winter is adding to the risk.

Children are particularly vulnerable at night without proper safeguards in place. Delays of up to five months in transferring children from the islands to the mainland are compounding their emotional and mental strain.

UNICEF is also calling for urgent policy and legal reforms to strengthen community-based care after years of economic hardship in Greece. For those children who have family elsewhere in Europe, UNICEF is urging other European countries to step up family reunification.