Four refugees drowned, four were rescued and a further six were still missing off the Greek island of Farmakonisi after their boat sank, the Greek coastguard said on Monday.
The vessel carrying the migrants sank on Sunday in an unknown location north of the island, they said in a statement.
In a separate incident on Sunday already reported by the coast guard, 11 people including six infants drowned when their boat capsized off the island of Samos, trapping them in the cabin.
The toll from drowning among thousands of refugees making the short but dangerous crossing from Turkey to Greece's outlying eastern islands has risen in recent weeks with the onset of colder weather. There were near-gale force winds blowing in the Aegean Sea at the weekend.
From the start of the year until Oct. 29, at least 435 people had drowned in the Aegean trying to reach Greece, according to data from the International Organisation of Migration, an inter-governmental body.
More than 580,000 refugees have entered Greece through its long sea border with Turkey this year, creating a tough logistical, financial and humanitarian challenge for the cash-strapped European Union member state.
Greece has agreed to temporarily house up to 50,000 refugees on its territory this year, with many in temporary housing subsidized by the United Nations.
The first relocation of a group of 30 asylum seekers from Greece to Luxembourg, which presently holds the rotating EU presidency, will take place on Nov. 4, the Greek Interior Ministry said on Monday. The migrants are from Syria and Iraq.
"It is a symbolic move designed to urge and encourage European governments to show active interest in receiving refugees," the ministry said.
As well as Luxembourg, Belgium, France, Germany, Cyprus, Lithuania and Finland have also shown an interest in the relocation program, the Greek ministry added.
(Reporting By Michele Kambas; Editing by Gareth Jones)