Greek coastguard officials are pursuing a grim search for survivors after a fishing boat overloaded with refugees and migrants capsized and sank in the Mediterranean Sea.

At least 79 people have so far been confirmed dead, and at the time of writing 104 people have so far been rescued. None of those rescued had safety equipment such as life jackets, the coastguard said.

There are fears that hundreds more are missing, and the boat – carrying hundreds of Syrian, Egyptian, Afghan, Palestinian, and Pakistani passengers for several days – may have had women and children locked in the hold when it capsized.

An official from Greece’s shipping ministry added that the boat sunk in a spot where the sea is 4,000 meters deep – one of the deepest areas of the Mediterranean – which means retrieving other victims may be impossible.

The sinking could be one of the worst ever recorded on the feared central Mediterranean migration route, which is the world’s deadliest.

Produced by Alexander Durie