At least four migrants have died after their boat was wrecked on an islet north of the island of Antikythera on Thursday, the Greek coast guard said.
They added that rescue crews had mounted an operation to rescue about 90 other people.
Greece is one of the main routes into the European Union for refugees and migrants fleeing war and poverty in the Middle East, Africa and Asia but most cross on rubber boats to islands close to the Turkish coast.
Thursday’s shipwreck is the second in the Aegean Sea this week, with rescue crews still searching for a second day for dozens of asylum-seekers feared missing after their boat sank off the island of Folegandros.
Antikythera and Folegandros are not on the typical route for migrants and officials said the boats, which set off from Turkey, were likely to have been aiming for Italy.
The United Nations refugee agency UNHCR called the Folegandros shipwreck “the worst” in the Aegean this year.
“This shipwreck is a painful reminder that people continue to embark on perilous voyages in search of safety,” Adriano Silvestri, the UNHCR’s assistant representative in Greece said.
“Such tragic deaths are avoidable, including through the establishment of regular and safe pathways that could prevent people from resorting to smugglers,” he added.
The UNHCR estimates that more than 2,500 people died or went missing at sea while attempting to reach Europe this year.
Greece, which was the frontline of Europe’s refugee crisis when it began in 2015, has since hardened its stance and boosted land and sea patrols to deter people from reaching its shores.
