Ankara - At least five migrants, including a baby, drowned as they tried to sail from Turkey to Greece, the Dogan news agency reported on Thursday.
The raft, which was transporting Afghan and Iranian migrants to the Greek island of Lesbos, foundered just 500 metres (550 yards) from the Turkish coast on Wednesday night.
Turkish coastguards managed to save nine of the migrants on board while two are still missing.
The fresh tragedy came as the European Union and Turkey are trying to firm up a proposed deal to end the worst migration crisis to hit the continent since World War II.
On Monday, Turkey proposed a deal that would see the EU resettle one Syrian refugee from camps in Turkey in exchange for every Syrian that Turkey takes from Greece, in a bid to reduce the incentive for people to board boats for Europe.
In return, Turkey wants billions of euros (dollars) in aid, visa-free access to Europe's passport-free Schengen zone and a speeding up of Ankara's efforts to join the EU - demands that go too far for some.
EU leaders hope to finalise the deal at a summit on March 17-18.
Turkey has become the main launchpad for migrants fleeing the five-year civil war in Syria in search of a better life in Europe.
Some 850,000 people landed in Greece from Turkey last year, often in desperately unseaworthy vessels.
Since January 1, more than 130,000 people have made the trip.