The agreement between the EU and Turkey to tackle the migrant crisis has formally come into effect.
Under the deal, migrants arriving in Greece are now expected to be sent back to Turkey if they do not apply for asylum or their claim is rejected.
The influx of people crossing to Greek islands grew ahead of the deadline, and Greece said immediate implementation of the deal would not be possible.
Meanwhile, thousands rallied against the deal in several European cities.
The deal says that for every Syrian migrant sent back to Turkey, one Syrian already in Turkey will be resettled in the EU.