Dozens of illegal migrants are feared dead after their boat sank off south-west Turkey, says Anatolia news agency.
A search for survivors began when an Iraqi passenger was rescued. Turkish efforts have drawn a blank, but a Greek operation is also said to be under way.
Up to 60 people from Iraq, Jordan and Afghanistan were thought to be on the boat when it left Marmaris in Turkey heading for the Greek island of Rhodes.
Turkey is on a major route for migrants trying to enter EU states illegally.
According to Turkish officials, the vessel is thought to have gone down about nine
nautical miles off the resort of Marmaris.
But it is not know exactly when the ship sank or how many people were aboard.
The Iraqi survivor, who was rescued on Saturday night and taken to Marmaris, was quoted by the Anatolia agency as saying there
were 55 people on the ship. However some officials put the number at about 60.
One regional official, Huseyin Aksoy, told Anatolia that coastguards had found 13 life-jackets and a small part of the ship's steering gear - but no survivors.
"We have completed search and rescue efforts in our territorial waters," Mr Aksoy said, but added that the Greeks were using helicopters and vessels to try to find survivors.
According to some estimates, up to a quarter of a million migrants from Africa, the Middle East and Asia try to get into the European Union every year via Turkey and Greece.
Those who do manage to get to Turkey either use land routes to travel on to Greece or Italy, or take to sea in what are often unseaworthy vessels operated by unscrupulous people-smugglers.