A boat carrying migrants from Turkey to Greece has sunk, killing at least 17 people, Turkish media say.
The boat capsized near the Turkish resort of Didim, the Anadolu and Dogan news agencies reported.
The International Organization for Migration says at least 321 migrants drowned trying to get to Greece between 1 January and 3 March.
Macedonia has set new restrictions on migrants coming from Greece, which may worsen the bottleneck on the border.
A search and rescue operation has been launched after the latest sinking in the Aegean Sea, and 15 people have so far been rescued, Anadolu reported.
Three children are believed to be among those who died.
More than 2,000 migrants, most from Syria, Iraq and Afghanistan, are arriving into Greece every day hoping to travel further north through Europe.
But some EU countries re-imposed internal border controls and Macedonia sharply reduced the numbers allowed to cross, leading to a build-up on the Greek side of the border.
On Sunday, Macedonia said it would no longer allow entry to anyone from who did not come from a city that was at war. As a result, anyone from Damascus or Baghdad is not allowed to pass.
On Saturday, Apostolos Tzitzikostas, governor of a northern border region, said the number of migrants on the frontier waiting to cross north into Macedonia had grown to at least 13,000.
Mr Tzitzikostas called for a state of emergency to be imposed on the border that could facilitate the delivery of aid.