Istanbul/Zurich: At least 18 people attempting to reach Greece drowned after their boat sank off the Turkish coast on Sunday, the state-run Anatolian Agency reported.
The Turkish Coast Guard, using speedboats and a helicopter, rescued 15 people and recovered 18 bodies in the Aegean Sea near the town of Didim, it said. Efforts continued to find more victims whose nationalities were not given.
Turkish Prime Minister Ahmet Davutoglu travels to Brussels on Monday for an emergency summit with European Union leaders to tackle illegal migration to member states, much of which occurs through candidate country Turkey.
A million people reached Europe through illegal routes in 2015, many fleeing economic and political turmoil in the Middle East, north Africa and Asia. Most of them came through Turkey, which borders Syria, Iran and Iraq.
Meanwhile, Austrian Chancellor Werner Faymann has urged Germany to set a clear limit on the number of asylum seekers it will accept to help stem a mass influx of refugees that is severely testing European cohesion.
The comments by the Social Democrat to the Kurier newspaper threaten to make even more complicated an emergency EU summit with Turkey on Monday on handling the worst refugee crisis in generations.
Austria - the last stop before Germany, the top destination for Migrants fleeing war and poverty in the Middle East and beyond - has already come under fire from the European Commission and human rights groups for capping its own intake of refugees.
"Germany too must give a number for the refugees it is prepared to take from the Syria and Turkey region. Germany must finally create clarity or else refugees will continue to head off in the direction of Germany," Faymann was quoted as saying.
"If you take the Austrian guidelines, Germany could give its quota at around 400,000. As long as Germany does not say that, it is clear what will happen. The refugees will continue to believe that they will be waved through."
In Berlin, a government spokesman declined to comment directly on Faymann, but referred to previous statements from Chancellor Angela Merkel in which she repeatedly rejected the introduction of such a national cap.
In a newspaper interview, Merkel defended her decision to keep Germany's borders open and reaffirmed her push for a joint European solution, including strengthening the continent's external borders and cooperation with Turkey to stop refugees from travelling on to Europe.
Austria, a country of 8.5 million people, got 90,000 asylum requests last year and has curtailed the number this year while imposing daily limits on the numbers it processes.
Faymann said Monday's summit was set to decide three things: improving cooperation with Turkey to fight human smugglers and return rejected asylum seekers, ending a policy of waving through refugees, and agreeing on a system for EU members to absorb asylum seekers with the help of the UN refugee agency.
In a separate newspaper interview, Austrian Defence Minister Hans Peter Doskozil said Austria did not want to take part in any quota system for distributing refugees among European countries because it had done enough on its own.
"We are taking the lion's share and taking in 37,500 asylum seekers this year alone. Now the others are called upon. Why should Austria take refugees from Greece?" Doskozil told the Oesterreich newspaper.