Egyptian nationals have been arrested on suspicion of belonging to the smuggling ring that arranged the deadly voyage.

State-run ERT TV said on Thursday the suspects were all Egyptian nationals.

Among the detainees was the captain of the overloaded and dilapidated vessel, a port source told AFP, even as new worries emerged that more people were missing in the disaster.

The arrests followed interrogations by coastguard officials at the southern port of Kalamata, where the 104 survivors from the shipwreck were being cared for. The sinking left at least 78 people dead.

The arrests were “the result of two days of interviews with the survivors, cross-referencing the information and honing down the possibilities of who among the survivors might have been part of the trafficking ring that profited from this enterprise and the profits are enormous,” Al Jazeera’s John Psaropoulos said.

Psaropoulos, reporting from Kalamata, said the charge of human trafficking in Greece, if it leads to a conviction, carries up to 20 years in prison.

The weight of the charges “would be affected also by the size of sums involved,” he said.

“If everyone on board paid $4,000-5,000 for their passage – and that’s what at least one relative of a missing person says he paid for his wife, and other reports have emerged of similar sums – then this human cargo was worth in excess of $3-3.5m,” he added.

Still searching

Fears have grown that the final toll could eventually run into the hundreds.

A huge search-and-rescue operation involving a dozen ships and three aircraft found no survivors since its initial phase early on Wednesday, when 104 people were rescued. No survivors were women.

“The chances of finding [more survivors] are minimal,” retired Greek coastguard Admiral Nikos Spanos told state-run ERT television.

Authorities fear that hundreds of people, including many women and children, were trapped below deck when the overcrowded trawler capsized in the night in deep waters about 75km (45 miles) offshore.

The UN migration agency estimated that the vessel was carrying 700 to 750 people, including at least 40 children, based on interviews with survivors. That could make the sinking one of the deadliest recorded in the central Mediterranean.

“We are witnessing one of the biggest tragedies in the Mediterranean and the numbers announced by the authorities are devastating,” the UN International Organization for Migration said.