At least 78 people have died and dozens are feared missing off the Coast of southern Greece after a fishing boat carrying migrants capsized and sank, authorities said Wednesday.

104 people have been rescued as a large search and rescue operation was launched in the area.

The Greek Coast Guard reported 78 dead and many more missing.

The Italy-bound boat is believed to have sailed from the Tobruk area in eastern Libya. The Italian coast guard first alerted Greek authorities about the approaching vessel on Tuesday.

At the southern port of Kalamata, dozens of rescued migrants were taken for medical assistance set up by the ambulance services and the United Nations Refugee Agency.

Libyan authorities have launched a major crackdown on migrants earlier this month across eastern Libya. In western Libya, authorities have raided migrant hubs in the capital, Tripoli and other towns with over 1000 migrants sent to state detention centres.

Mediterranean smugglers are increasingly taking to international waters off the Greek mainland in a bid to avoid local coast guard patrols in dangerous missions, with many stranded boats sending distress calls to Greek coast authorities in the recent past.