Three people have died after a boat carrying 73 refugees capsized off the northwestern coast of Turkey, Turkish state media quoting the coastguard said.
The coastguard said that all other refugees were saved in Monday's shipwreck - the first of two deadly incidents on Monday.
The semi-official Anatolia Agency said that the group, composed of Afghans and Syrian, had sailed from the Ayvacik coast of Canakkale province to reach the nearby Greek island of Lesbos when their boat sank.
Separately, Greece's coastguard was searching on Monday for at least six people missing at sea after the dinghy they were using to enter Greece clandestinely from Turkey overturned off the coast of the eastern Aegean island of Lesbos, the AP news agency reported. They said one body was recovered from the same wreck.
The coastguard said it had picked up 877 people in 30 search and rescue operations from Friday morning to Monday morning off the coasts of the islands of Lesbos, Chios, Samos and Kos. The figures do not include the hundreds who manage to make it to the islands themselves, mostly in inflatable dinghies.
Greece has been overwhelmed by an influx of mainly refugees from Syria and Afghanistan reaching its islands from Turkey, with more than 160,000 entering the country so far this year.
The vast majority, if not all, do not want to remain in Greece, a financially broken country where unemployment runs at more than 26 percent. Instead, the refugees seek to make their way north towards more prosperous northern and western European countries such as Germany, Sweden and the Netherlands.
French President Francois Hollande and Germany's Chancellor Angela Merkel are scheduled to discuss quotas for accepting refugees at their meeting on Monday afternoon in the German capital Berlin.