Thousands of migrants stranded on Greek islands should be quickly transferred to the mainland or other European countries due to cold temperatures and poor living conditions, the United Nation's refugee agency (UNHCR) said on Friday.
About 15,000 people living in the overcrowded island camps do not have enough heating or supplies to keep warm during the winter months, the UNHCR said.
"Even with recent efforts to improve matters, conditions at many sites on the islands remain very poor," UNHCR spokesman Adrian Edwards said at a press briefing in Geneva.
"The need for better protection will become all the more acute this weekend when temperatures on the islands are expected to drop. We are worried."
Edwards said aid workers have been installing electric heaters and insulation, and distributing additional thermal blankets and sleeping bags.
Last Wednesday, Greek authorities vowed to improve its island camps, after violent protests from migrants angry over the slow processing of asylum requests and living conditions.
More than 1 million people fleeing war and conflict in the Middle East, Africa and Asia, arrived in Greece by sea between 2015 and 2016, the U.N.'s migration agency, IOM, says.
The number making the sea crossing from Turkey to Greece fell sharply last year under a European Union (EU) deal with Turkey. The agreement stipulates that people arriving after March 20 are to be held on five Aegean islands and sent back if their asylum applications are not accepted.
Under a 2015 scheme, EU member states agreed to take in 66,400 migrants from Greece within two years, but so far, only 7,760 asylum seekers have been moved, the UNHCR said on Friday.