Some 100 people were rescued after the packed fishing boat capsized in international waters in the Ionian Sea in an operation complicated by strong winds, the coastguard said.
But there were fears for scores of women and children, as most of the survivors were men, state TV ERT reported — which is unusual for a migrant group of this size.
A survivor told hospital doctors in the port city of Kalamata, where the rescued were taken, that he had seen a hundred children in the boat’s hold, ERT said.
“The fishing boat was 25-30 meters long. Its deck was full of people, and we assume the interior was just as full,” coastguard spokesman Nikolaos Alexiou told ERT.
“We do not know what was in the hold… but we know that several smugglers lock people up to maintain control,” government spokesman Ilias Siakantaris told ERT.
Siakantaris said there were reports, that could not be confirmed at present, of up to 750 people on board.
The International Organization for Migration said in a tweet: “We fear more lives were lost. Initial reports suggest up to 400 people were onboard.”
The coastguard spokesman said the search and rescue effort would continue during the night with flares fired by a C-130 military transport plane.
The boat’s engine gave up shortly before 2300 GMT on Tuesday and the vessel capsized in the deepest waters of the Mediterranean, Siakantaris said.
The boat sank in around 10 to 15 minutes, he added in a separate note to the media.
The survivors are mainly from Syria, Pakistan, and Egypt, Alexiou said.
Greece’s head of state, President Katerina Sakellaropoulou, visited the port of Kalamata to confer with senior officials on the rescue and accommodation response.
Greece is under an interim government until June 25 elections. The office of interim prime minister Ioannis Sarmas declared three days of mourning, adding that the nation’s thoughts were “with all the victims of ruthless smugglers who take advantage of human misfortune.”
Greece has been a main landing point for people seeking to reach Europe from Africa and the Middle East
European Commission head Ursula von der Leyen said she was “deeply saddened by the news of the shipwreck off the Greek coast and the many reported deaths” and “very concerned by the number of missing people.”
“We must continue to work together, with member states and third countries, to prevent such tragedies,” she said.