Greek authorities said they were not aware of any boat in distress near the island.
The bodies of seven suspected migrants have been found on the shore of the Greek island of Lesbos, the coastguard has said.
Authorities said the remains of three men and three women were found early on Tuesday morning near the island’s main town of Mytilene.
"Four bodies were discovered" by a passer-by on the beach of Ano Skala, the coastguard said, while "two others were recovered from the water".
A seventh suspected victim was found on Wednesday, less than a kilometre from the town's port.
Officials believe that the people were migrants who died while trying to reach the Greek island from the nearby Turkish coast. None of the six victims had been wearing life jackets, they added.
There were no signs of a shipwreck and Greece said it had not received any emergency calls about a boat in distress in the Aegean Sea.
A search and rescue operation was launched in the area with three patrol boats, a helicopter and nearby ships to look for potential survivors and more victims.
Thousands of people fleeing conflict and poverty in Africa, the Middle East and Asia attempt to reach the European Union through Greece.
Many make the short but often perilous journey in unseaworthy dinghies from the Turkish coast to nearby Greek islands.
NGOs have repeatedly accused the Greek government of "illegal migrant pushbacks" at the Turkish borders. Athens has rejected the allegations.