At least 12 people died Saturday when a boat loaded with asylum-seekers sank in the Ionian Sea, the Greek coastguard said.
"So far 12 bodies have been recovered. The search and rescue operation continues," the coastguard said, adding that over 20 people had been found alive.
The boat, with around 50 people on board, took on water near the island of Paxi during an apparent attempt to reach Italy.
There were no immediate details on the identity of those on board.
Six coastguard patrol boats and two navy helicopters were engaged in the continuing rescue effort, authorities said.
Four passing cargo ships were also assisting the operation, the coastguard said.
Thousands of migrants and refugees have died in recent years while attempting to cross the Mediterranean Sea in small, overloaded boats, Agence France Presse reported.
Twenty-two people have died or are still missing in migrant boat sinkings in the Mediterranean just this month, according to the International Organization for Migration.
Another 73 persons were rescued in separate incidents in the Aegean between Friday and Saturday, the Greek coastguard added.
