Turkish police have detained 129 illegal immigrants after their ship began sinking.
Authorities said the ship had no chance of reaching Italy.
Authorities suspect the captain and crew members, who deserted the boat near the coastal town of Kas, could have mixed among the immigrants.
Some immigrants tried to escape but paramilitary police captured them.
"The ship neither has a name nor a flag on it," said governor Halil Ibrahim Kayapinar. "But we suspect it to be a Turkish one."
Mr Kayapinar said the ship reportedly left the Turkish coastal town of Alanya, 125 miles east of Kas on Monday but could not navigate farther when its cargo sections submerged in water. It is not clear why the ship began sinking.
He says the immigrants are in good condition despite spending four days in the sea.
On Thursday, Turkish and Greek coast guards intercepted a boat in the Aegean Sea, detaining about 100 illegal migrants aboard. The immigrants, mostly Iranians, said they had paid US$2,500 per person for the trip from the Aegean resort town of Bodrum to the nearby Greek island of Kos.