Greece: Twelve migrants die off coast
Greece has increased controls on its land border with Turkey - meaning sea-borne traffic has increased
The Greek authorities say at least 12 migrants, four of them children, have drowned after their inflatable boat sank in the Ionian Sea.
They were alerted to the incident early on Friday by 15 survivors who made it to shore on the island of Lefkada.
There is no indication of where the migrants came from but officials say it is likely they were heading for Italy.
The mayor of Lefkada said it was unclear why the boat sank as weather conditions were good and winds light.
"Some of the survivors managed to swim to the shore and call for help. They were not sure exactly how many people were on the boat so we still don't know if there are others still out there'', Mayor Costas Aravanis told the AP news agency.
The Merchant Marine Ministry said the migrants were aboard a plastic boat that was 7-8m (23-26ft) in length.
A search and rescue operation is under way to try to locate more possible victims and survivors.
Greece is one of the main destinations for migrants and refugees trying to enter the European Union.
Correspondents say there has been a sharp increase in sea-borne refugee traffic over the past year, because of stricter controls on the Greek-Turkish northern land border and the ongoing war in Syria.
This latest incident comes amid increased scrutiny of the European Union's immigration policy following the death of almost 400 asylum seekers who recently drowned off the Italian island of Lampedusa in two separate incidents.