At least 44 people, including 20 children, have died after their boats sank on their way from Turkey to Greece today, with dozens of other migrants reported missing, coastguard officials in Greece and Turkey said.
The Greek coastguard said they had rescued 74 people after two boats ran into trouble off the Greek Aegean islands of Farmakonisi and Kalolimnos in the early hours.
They recovered the bodies of 17 children, 17 women and 10 men. A search operation, backed by a helicopter from EU border agency Frontex, was under way for dozens of people still missing from the boat that capsized off Kalolimnos.
Separately, the Turkish coastguard said they had found the bodies of three children today after a third boat sank near the seaside resort of Didim, the Dogan news agency reported.
People fleeing war and misery in the Middle East and elsewhere - many of them Syrian refugees - are still arriving from Turkey in flimsy boats in their thousands every day, despite the dangers and the harsh winter weather.
At least 113 migrants have died in the Aegean already this year, according to the International Organisation for Migration.
The IOM estimates that some 37,000 migrants have reached Greece by sea so far this year, hoping to start new lives in Germany, Sweden and elsewhere in the European Union.
Yesterday at least 12 migrants, including children, drowned off the Turkish coast as their boat tried to reach Greece. The Turkish coastguard rescued 28 people.
Turkey, which is home to some 2.2 million refugees from Syria's civil war, has become a hub for migrants seeking to reach Europe, many of whom pay people smugglers thousands of dollars for the risky crossing.
Ankara reached an agreement with the EU in November to stem the flow of refugees heading to Europe, in return for financial assistance.
Brussels vowed to provide €3bn as well as political concessions to Ankara in return for its cooperation in tackling Europe's worst migrant crisis since World War II.
German Chancellor Angela Merkel - whose country took in 1.1 million asylum seekers in 2015 - met Turkish Prime Minister Ahmet Davutoglu today, with the migrant crisis top of the agenda.
During the meeting, Ms Merkel said she had obtained a pledge from Turkey to "do everything" to cut the record number of migrants arriving in Europe.
After talks with Mr Davutoglu in Berlin, Ms Merkel said they had signed a joint communique under which "the Turkish government will do everything to reduce the number of refugees" crossing into the European Union.
"The Prime Minister emphasised the commitment of the government of Turkey to undertaking all possible efforts to substantially reduce the number of irregular migrants in the near future," a statement released after a news conference said.
It added that Turkey "pledged to facilitate the readmission of irregular migrants not in need of protection".
In exchange, Turkey could count on German support for easing EU visa requirements for Turkish nationals visiting the Schengen area.
Ms Merkel and Mr Davutoglu "emphasised their commitment towards meaningfully advancing the negotiations between Turkey and the EU on visa liberalisation with a view to lifting the visa requirements for Turkish citizens to the Schengen area by October 2016", the statement said.
Today's talks were key for Ms Merkel, who faces intense pressure at home to impose a cap on Germany's refugee intake at a time when European public opinion is hardening against asylum seekers.
Ms Merkel has described Turkey, which not only shares a border with war-torn Syria but is also a launch pad for thousands of migrants, as crucial to any solution to the crisis.
Sutherland says mass migration 'unavoidable reality'
Mass cross-border migration is an "unavoidable reality" and it is "impossible to stop" the flow of refugees in need of sanctuary, Peter Sutherland, the UN's special representative for migration said.
The former EU Commissioner said the world needed to accept millions of people fleeing conflicts in Syria and elsewhere and find ways to live together.
He was speaking on a visit to Bangladesh for the Global Forum on Migration and Development.
The forum in Dhaka takes place as Europe is facing its biggest migration crisis since World War II, with more than a million asylum seekers arriving in Germany alone in 2015 - triggering a fierce backlash.
"We must find ways to be living together. Today [migration] is an unavoidable reality, we are living in the era of globalisation," Mr Sutherland said.
"It is impossible to stop. Those who believe in some way that we can erect fences and stop migration are living in cloud cuckoo land," he said.
Turkey is currently hosting 2.2 million Syrian refugees, while between 2,000 and 3,000 people arrive daily in the main European landing point of Greece, although many die making the journey.