A European Union plan to remove failed asylum seekers from Europe is already under threat, two days before it is due to be implemented.
Hundreds of migrants have broken out of a holding centre on the Greek island of Chios.
It is seen as a protest at plans which will see most of them sent back to Turkey.
It is reported refugees tore down part of a razor wire fence.
Under a new EU deal from Monday, people will have to go back to Turkey if their asylum applications are rejected.
In Dikili in Turkey, where many migrants are due to be sent, locals have gathered to protest their arrival.
Its mayor, Mustafa Torun, says the area is not big enough.
Reporter Mark White says the whole system seems a bit shambolic: "There isn't any centre to speak of that would receive these migrants who are returned to Turkey and of course we're hearing that some of these detention camps on some the Greek islands, they cannot cope with the increased numbers of people they have".
This footage shows people leaving the centre.