At least 16 people, including two children, have drowned when an inflatable boat sank in the eastern Aegean Sea between Greece and Turkey, according to Greek authorities.

Greece's coastguard said on Monday that the bodies of nine people - six women, two men and a child - had been recovered overnight from Greek waters off the island of Lesbos, while Turkish authorities found the bodies of a further six men and a child in Turkish waters.

Two women from the boat were rescued and several other people were believed to be missing. Several vessels are continuing the search.

The boat was believed to have set sail from Turkey late on Sunday. The alert was raised on Monday morning by a Greek navy vessel that spotted bodies in the water.

Citing survivors, the United Nations refugee agency UNHCR said 25 people were on board. Two survivors, one of whom is pregnant, were from Cameroon and the Democratic Republic of Congo, the agency said.

Hundreds of thousands of people, most of them fleeing the Syrian conflict, have crossed into Greece from the nearby Turkish coast, hoping to head to European countries.

But a European Union-Turkey deal reached last year - in which those arriving on Greek islands face deportation back to Turkey - has significantly reduced the number of people attempting to cross the Aegean.

An average of 20 arrive on Greek islands each day.

Most undertake the short but dangerous journey on overloaded inflatable dinghies or occasionally sailboats.

Lesbos is located fewer than 19km from Turkish shores.