Rescuers pulled bodies from the Aegean sea on Wednesday as the death toll from Greece's worst maritime disaster in 35 years climbed to at least 62.
The ferry Express Samina ran into a rocky islet off the holiday isle of Paros and sank in gale-force conditions late on Tuesday. Hundreds of Greek and foreign passengers were hurled into the rough waters.
Twenty-nine people were missing, the Greek Merchant Marine Ministry said.
Survivors described a night of terror, clutching life vests and floating debris, and of fishermen
"heroes" who came to their rescue.
An all-night, all-day rescue operation - reinforced by passing British warships - combed the seas off Paros, a popular tourist destination in the idyllic Cycladic island chain southeast of Athens, for survivors in gale force winds.
Officials said 443 people had been rescued. There was confusion about how many people had been on board the ferry, with suggestions that children and last minute passengers may have inflated the 510 registered passengers and crew.
A Greek Coast Guard official died of a heart attack during rescue operations.
It was the deadliest maritime disaster in Greece since the passenger ferry Iraklio went down in 1965, killing 217 people.
Government officials and survivors began asking how a ferry could collide with a charted island.
A Paros senior Coast Guard official provided only that, "there was a lighthouse on the rock."
Greek Prime Minister Costas Simitis expressed grief and pledged a full investigation into the sinking.
"I assure the Greek people that plenty of light will be shed on this tragedy that has shaken all of us," he said in a statement.
Justice Minister Michalis Stathopoulos told parliament he ordered the investigation after speaking with the Prime Minister.
"I spoke with the Supreme Court prosecutor in order to launch criminal proceedings against the shipowners and ship operators as well as those in charge of the ship," Stathopoulos said.
The Coast Guard on Paros detained five crew members, including the captain, for questioning.
The ship's owner, Minoan Flying Dolphins
, a subsidiary of Minoan Lines
, rejected claims by a seamen's union that the ferry was not seaworthy, saying the Merchant Marine Ministry had investigated and approved its sailing.
"The company declares that it...will make available all of its services to shed light on the reasons for the tragic accident," it said in a statement.
It was reported today that a Minoan representative had been called to answer questions at the Piraeus Port Authority.
Parliament interrupted regular proceedings and opposition parties demanded a full investigation.