At least 79 people have died and more than 100 have been rescued after their fishing vessel capsized off the coast of southern Greece.
But survivors and Greek officials say that hundreds more migrants were on board.
The government says this is one of Greece’s biggest migrant tragedies, and has declared three days of mourning.
The boat went down about 80 km (50 miles) south-west of Pylos after the coastguard said it had refused help.
The coastguard said the boat had been spotted in international waters late on Tuesday by an aircraft belonging to EU border agency Frontex. No-one on board was wearing life jackets, it added.
Quoting a timeline provided by the shipping ministry, Greek public broadcaster ERT said authorities had made contact with the boat via satellite phone on several occasions and offered help, but were repeatedly told: “We want nothing more than to go on to Italy.”
A few hours later, around 01:40 on Wednesday (23:40 GMT Tuesday), someone on the boat is said to have notified the Greek coastguard that the vessel’s engine had malfunctioned.
Shortly after, the boat capsized, taking only ten to fifteen minutes to sink completely. A search and rescue operation was triggered but complicated by strong winds.