Greek authorities were bracing for a backlash on Sunday from migrants who will be forced to return to Turkey next week under a migration deal between the European Union and Ankara.
Under a deal struck between the EU and Turkey last month, migrants who arrived in Greece after March 20 who do not apply for asylum or fail to qualify will be returned to Turkey starting Monday.
For every migrant sent back to Turkey, one Syrian refugee will be directly taken from Turkey and resettled in Europe.
Heavy security precautions are being taken for the Monday launch of the exchange. "For each migrant being expelled, we will delegate one police officer as a chaperone," a Greek coastguard officer told dpa.
Migrants likely to be sent back to Turkey rallied in protest on the islands of Lesbos and Chios on Saturday, denouncing the returns as "deportations."
Hundreds broke out of a camp on Chios on Friday and were camped out in the island's main port on Sunday, demanding to be taken to the Greek mainland and not back to Turkey.
The Turkish government expects approximately 400 refugees and migrants to arrive on Monday from Greece, Interior Minister Efkan Ala told journalists in Bodrum, adding that the number of arrivals could rise.
The new arrivals will be accommodated in reception centres across different districts, with Syrians subsequently being distributed across the country, the minister said.
Migrants of other nationalities will be deported to their countries of origin, Ala said.
Meanwhile, local authorities in the west Turkish harbour of Dikili said they were not ready to accommodate the hundreds of refugees expected to arrive on Monday.
"I myself as mayor have received no information at all from the responsible parties in Ankara regarding the migrants," Dikili Mayor Mustafa Tosun told dpa.
Hundreds of protesters gathered in Dikili on Saturday to protest the migrants' arrivals. A dpa reporter reported seeing three tents set up for the migrants at the harbour.
"We don't know what the government has in mind," a store owner in Dikili said. "The authorities don't seem very prepared."
According to Greek authorities handling the refugee crisis, more than 52,500 refugees and other migrants were stranded in Greece as of Saturday.
The bottleneck in Greece has intensified after countries further north along the so-called Balkan route to northern and western Europe closed their borders to people without valid travel documents.
Also on Monday, the first Syrians to be resettled under the deal in Europe are expected to arrive in Germany, the Netherlands, France, Finland and prospectively Portugal.
The exchange of migrants is meant to apply to a maximum of 72,000 people.