At least twelve migrants drowned and 21 were rescued, when their boat capsized off the Greek island of Paxos in western Greece, Greece's Coast Guard reported.
A spokesperson for the Coast Guard stated that initial reports suggested that 50 people were on the boat.
Four merchant ships, six coast guard ships and a helicopter were called in to search the area for more survivors.
Authorities said someone from the boat had called the 112 emergency number at 9:15am (local time) on Saturday.
There are no further details about the migrants.