Four crewmen and 25 passengers remain unaccounted for three days after the Italian cruise ship Costa Concordia crashed off Tuscany, the coast guard said yesterday.

“An hour ago I received a report from the (local) Grosseta administration that 29 people remain unaccounted for,” coastguard chief Marco Brusco said on Italian television late yesterday evening, revising upward an earlier estimate of about 15.

Meanwhile, Italian divers and mountain rescue teams yesterday scoured the wreck of the luxury liner as hopes faded of finding any more survivors on board.

Choppy seas forced a temporary evacuation of the stricken 17-deck Costa Concordia for several hours after the half-submerged ship slipped on a rocky shelf under the sea, sparking fears that the giant hulk could sink entirely.

Emergency workers said at least 15 people were still missing. The death toll also rose to six after the body of a man was found by divers early yesterday.

“The conditions inside are disastrous. It’s very difficult. The corridors are cluttered and it’s hard for the divers to swim through,” Rodolfo Raiteri, head of the coastguard’s diving team said.

Three of the victims – two Frenchmen and one Peruvian crew member – drowned after jumping into the chilly winter Mediterranean waters along with dozens of others in a chaotic evacuation in the Friday the 13th tragedy.

The local mayor voiced hope of finding more people alive, but also warned that the stricken vessel, which hit rocks and keeled over off Giglio island, was an “ecological timebomb” in the pristine waters of a marine nature reserve, adding that there were 2,380 tons of fuel on board. “You never know in the labyrinth of that ship. An air pocket could have allowed people to survive a few days,” mayor Sergio Ortelli said.

The head of the company which owns the monster vessel said it had hit a rock as a result of an “inexplicable” error by the captain, Francesco Schettino, who was arrested on Saturday along with first officer Ciro Ambrosio.

“He carried out a manoeuvre which had not been approved by us and we disassociate ourselves from such behaviour,” said Pier Luigi Foschi, the boss of Costa Crociere. But Mr Foschi also paid tribute to the other crew members, saying they had “all behaved like heroes”.

The Costa Concordia was carrying more than 4,200 people when it ran aground shortly after starting a seven-day Mediterranean cruise, just as many passengers were having dinner.

Island residents said the ship was sailing far too close to Giglio and hit a reef known as the School Rocks, well known to inhabitants.

The Corriere della Sera reported yesterday that the captain had passed close to the island’s rocky shores to please the head waiter who comes from Giglio. It quoted witnesses as claiming the waiter had warned Capt Schettino just before the accident happened: “Careful, we are extremely close to the shore.”

Environment Minister Corrado Clini meanwhile warned that “urgent action” was needed as the wreck posed a serious risk to the area around Giglio. Crews yesterday began putting down anti-spill booms as fears of a leak rose and local officials called for strict curbs in the future on shipping routes through the area of outstanding natural beauty. The Dutch ship salvage and environmental disaster management company Smit said it had been hired by the owners of the Costa Concordia to pump out fuel from the ship. The operation is expected to start within days.

The 114,500-ton liner could be refloated with the help of huge inflatable buoys once the fuel is pumped out and leaks plugged, Costa Crociere said.

But company boss Mr Foschi said the operation if it goes ahead would be “one of the most difficult in the world.”

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