Nine Egyptian nationals suspected of human trafficking were arrested by the Greek Hellenic Coast Guard in connection with the deadly shipwreck that occurred off the country's southwestern coast leaving at least 78 passengers dead. state media reported.

All nine were among the survivors of the tragedy, according to the Greek national news agency AMNA.

The latest press release issued by the Hellenic Coast Guard puts the number of survivors at 104, reports Xinhua news agency.

It is yet unclear how many people were on board the fishing boat that sank in the early hours of Wednesday in international waters about 47 nautical miles off the town of Pylos in southwestern Greece.

Greek authorities have not confirmed estimates reported in the media that up to 750 people may have been on board.

Survivors said that they had departed from Libya and were heading to Italy, according to Greek national broadcaster ERT.

The Hellenic Coast Guard was alerted by the Italian authorities and located an overloaded boat which rejected any aid, Nikolaos Alexiou, spokesperson of the Maritime Affairs and Insular Policy Ministry, told local SKAI television on Thursday.

Greek authorities did not try to intervene by force to lead the boat to a Greek port, fearing that could cause capsizing, he said.

A sudden shift in weight as crammed passengers moved around may have caused the capsizing and sinking of the boat a few hours later, he added.

A three-day national morning for the victims of the tragedy began in Greece on Wednesday evening.

Greece and other Mediterranean countries have been at the forefront of the influx of refugees and migrants since 2015.

The often deadly trips across the Mediterranean have so far claimed the lives of thousands, according to the UN Refugee Agency. (IANS/NS)