The latest deaths in the Aegean Sea came as Athens angrily defended its handling of the mounting refugee crisis in Europe.
Four babies and 10 young children — five boys and five girls — were among the 112 people on the stricken boat when it sank off the southern Aegean island of Farmakonisi, Athens News Agency reported.
Eight of the victims were found by coastguard frogmen in the hold of the boat.
Another 68 people were plucked alive from the sea while a further 29 managed to swim to safety on a beach on the island, the coastguard said.
The coastguard was also still searching for four children missing after another boat capsized on Saturday off Samos, a Greek island just off the Turkish coast.
The latest tragedies follow the death of a Syrian toddler whose lifeless body was photographed washed up on a Turkish beach, becoming a heartwrenching symbol of the plight of refugees fleeing war.
The International Organisation for Migration has said more than 430,000 migrants and refugees had crossed the Mediterranean to Europe so far in 2015, with 2,748 dying or going missing en route.
Interim Prime Minister Vassiliki Thanou on Sunday branded criticism of Greece, which has been on the frontline of the surge of migrants trying to reach Europe, as “unacceptable”.
“Greece is strictly applying European and international treaties without ignoring the humanity of the situation,” she said on a visit to Lesbos, an island which has been struggling with the massive influx.
German Chancellor Angela Merkel on Saturday called on Athens, already grappling with a deep economic crisis, to make more effort to protect the EU’s external borders.
“We have a second external border, that’s between Greece and Turkey, where we need protection. And this protection is at the moment not being guaranteed,” she said.
“Greece needs to take its responsibility… we will also speak with Turkey.”