But under lengthy questioning Tuesday by Italian prosecutors, Schettino denied he had left the Costa Concordia and said his actions as the boat was going down near the Tuscan island of Giglio had saved many lives.

"The captain defended his role on the direction of the ship after the collision, which in the captain's opinion saved hundreds if not thousands of lives," his lawyer Bruno Leporatti said. "The captain specified that he did not abandon ship."

The Corriere della Sera daily said Schettino told prosecutors that he was at the helm when disaster struck, but later fell into the sea and could not get back on board the tilting vessel.

Leporatti backed the claim, telling journalists: "The ship in that moment was tilted over by 90 degrees."

He also said the captain "carried out a brilliant manoeuvre" after the collision, and had "kept his wits about him", managing to steer the vessel towards the shore and "save a number of lives".

But according to investigators, the flooded engine rooms would have made it impossible for Schettino to navigate the 114,500-tonne ship, which drifted closer to a tiny port on Giglio before capsizing.

In the Livorno port authority recording, an increasingly strident port official tells Schettino: "Get back on board now, for f**** sake... You must tell us how many people, children, women and passengers are there."

The official asks: "What are you doing? Are you abandoning the rescue?"

Schettino, who was arrested along with his first officer, Ciro Ambrosio, on Saturday, has yet to be formally charged, while a judge ruled Tuesday that he should be placed under house arrest, Leporatti said.

Chief prosecutor Francesco Verusio said Schettino was a flight risk and risked 15 years in prison.

The grilling of Schettino came as another five bodies were discovered after the Italian navy used explosives to blow seven holes in the upturned hull of the Costa Concordia, bringing the death toll to 11.

About two dozen people are still missing.

"The five victims are a woman and four men, who could be passengers but we are not sure, they are between 50 and 60 years old," said coastguard spokesman Filippo Marini. He said the victims were wearing life jackets.

Earlier, officials had said that 12 Germans, six Italians, four French, two Americans, one Hungarian, one Indian and one Peruvian were still unaccounted for. There were also reports of a missing five-year-old Italian girl.

The dead identified so far include two French passengers, an Italian and a Spaniard and one Peruvian crew member.

Meanwhile it emerged Tuesday that one of the survivors was the granddaughter of a survivor of the Titanic disaster in 1912 when the passenger liner sank on its maiden voyage from Southampton to New York.

"It was like re-living history, it was horrible, I was really shocked," Valentina Capuano, 30, told the Italian daily La Repubblica.

About 4,200 people were on board when the ship went down shortly after it had left a port near Rome at the start of a seven-day Mediterranean cruise, and survivors have spoken of scenes of confusion and panic on board.

The Italian press reported Tuesday that as the vessel began to keel over, the crew initiated the evacuation procedure themselves -- 15 minutes before Schettino eventually gave the command.

But in his meeting with prosecutors, "the captain explained his behaviour, his decision, his choices during that phase of emergency", lawyer Leporatti told reporters outside the court in the provincial capital Grosseto.

Asked what caused the disaster, Leporatti replied: "He found a rock along his route."

Schettino has been widely criticised after reports emerged that he ordered an unauthorised sail-by close to the island, which was not on the cruise's itinerary, to please a crew member who hails from Giglio.

"It was bravado, Schettino was showing off, clowning around, it was incredibly stupid. I would sentence him not once but 10 times," said a former captain who worked with the ship's owner, Costa Crociere.

Costa Crociere, Europe's largest cruise operator, said Monday that the accident occurred as a result of an "inexplicable" error by the captain and distanced itself from the actions of their employee.

More than 70 Italian passengers have joined a class action suit against the owner, consumer rights association Codacons said Tuesday.

Five French survivors have also lodged complaints or plan to do so in three different actions.

Mario Palombo, a former captain of the Costa Concordia with whom Schettino served as first mate for four years, told investigators that he was "too high-spirited and a dare devil".

An officer on the Concordia, Martino Pellegrino, said that Schettino, from the Amalfi coast region near Naples, ruled with "an inflexible authority ... against which no one could make their voices heard".

As fears rose of an environmental disaster if the ship's fuel tanks rupture and leak, Marini said crews had laid down absorbent booms after noticing "an iridescence" in the water off Giglio, a marine sanctuary and popular holiday spot.

Forecasts say a storm is expected to lash the rocky island on Thursday, prompting concerns that the semi-submerged ship could sink entirely.

Dutch salvage company Smit began assessing the site on Tuesday and plans to begin pumping out the fuel from the Concordia's tanks this week, although it said the operation would take at least three weeks.

Officials said the giant ship itself could then be taken off Giglio in an unprecedented operation using massive floats.