The number of migrants reaching Greece has sharply risen, with at least 374 arriving from Turkey over the weekend, the country's migration crisis authority said on Monday.
The reason for the rise was unclear, however local media have speculated smugglers are increasing their numbers ahead of a forecast bad spell of weather.
Greece has previously seen the influx of migrants to its islands drop to a daily average of less than 50 migrants since the EU and Turkey implemented a refugee deal in April.
Nevertheless Greece's working group for the refugee crisis has reported sudden spikes in migrant numbers.
Migrants who disembark on Greece's eastern Aegean islands are not allowed onto the mainland. They must instead wait several months until their asylum applications are accepted or otherwise face deportation back to Turkey.
The so-called hotspots set up for the arrival of migrants on Greek islands are overflowing with a total of 12,200 people. The centres on the islands of Lesbos, Chios, Samos, Leros and Kos are intended to hold 7,450 people.