Twenty-four people attempting to cross to Europe from Turkey drowned when their boat sank off a Greek island, the Greek coast guard said on Thursday, raising to at least 80 the number of migrants and refugees to have died at sea in the past week.

More than 900,000 people fleeing Syria, Afghanistan and other war-torn or impoverished countries arrived in Greece from Turkey last year, often risking the short but dangerous sea crossing in overloaded boats.

The latest accident occurred late on Wednesday north of the island of Samos, close to the Turkish coast. The coast guard said a man who managed to swim ashore told Greek authorities the boat had been carrying 40 to 45 people.