Fears are growing for the 29 people now listed as missing after the Costa Concordia crashed into rocks off Italy’s west coast on Friday night.
Emergency crews have worked through the night at the wreck of a stricken cruise ship.
Six people are known to have died in the disaster up to now.
Local coast guard chief Marco Brusco said there was just a “glimmer of hope” that survivors could be found.
The ship’s owners have blamed Captain Francesco Schettino for Friday’s crash, saying he changed course towards an island.
Captain Francesco Schettino, 52, has been detained on suspicion of manslaughter and a judge is due to decide shortly whether he should remain in custody.
Italy says it will declare a state of emergency over the incident, and provide funding to help avert any environmental disaster.
The Italian environment minister said liquid was leaking from the ship, but it was unclear if it was fuel.
Meanwhile, Italian officials have denied a newspaper report that a seventh body had been found overnight on the vessel.
Italian Coast Guard officials said the number of people believed to be missing had jumped to 29 from the previous estimate of 16, but gave no reason for the change.
The missing are thought to include four crew members, as well as passengers from the US, Germany, France and Italy.
On Monday, the Costa Concordia’s owners, Costa Cruises, said Captain Francesco Schettino hit the rocks because he deliberately steered the ship towards to Giglio Island.
Prosecutors also claim that Francesco Schettino was responsible for the disaster.
“The captain is in a very difficult position because we are sure enough that he abandoned the ship when many passengers were still waiting to be evacuated,” said prosecutor Francesco Verusio.
A transcript purportedly of conversations between the captain and the coastguard has emerged in the Italian media – apparently drawn from one of the ship’s black box recorders – which appears to corroborate the claims that the captain left the ship before all the passengers escaped.
Capt Francesco Schettino has denied wrongdoing and says the rocks were not on his charts. He has insisted that he and his crew were the last people to leave the vessel.
His lawyer, Bruno Leporatti, said his client was “overcome and wants to express his greatest condolences to the victims”, adding that the captain had carried out a dangerous manoeuvre that had actually saved lives.
Costa Concordia, carrying 4,200 passengers and crew, had its hull ripped through when it hit rocks late on Friday.
Some people were forced to swim for land as the angle of the ship made boarding lifeboats impossible.
German media have reported that 12 German passengers are still missing, and US officials have appealed for information about two Americans – Jerry Heil, 69, and his wife Barbara, 70, from White Bear Lake, Minnesota.
Six Italians, two French couples and a Peruvian are also reported to be unaccounted for.
Teams of specialist divers have been helping with the rescue mission, but they have been hampered by bad weather, which has been moving the ship in the water.
Saturnino Soria, father of Peruvian Erika Soria, who was working as a waitress on the ship, insisted that the search operation should continue.
“I haven’t received any precise information about her – nothing from yesterday or today – it seems the situation has become worse for my daughter,” he said.
Rodolfo Raiteri, head of the coastguard’s diving team, was quoted by news agency AFP as saying that conditions inside the vessel were “disastrous”.
“It’s very difficult. The corridors are cluttered and it’s hard for the divers to swim through,” he said.
But the local mayor voiced hope of finding more people alive.
“You never know in the labyrinth of that ship. An air pocket could have allowed people to survive a few days,” Sergio Ortelli was quoted by AFP as saying.
Meanwhile, the shipping newspaper Lloyd’s List said it had been able to trace the course of the Costa Concordia though information from satellites.
The paper issued a graphic comparing Friday’s sailing with an earlier sailing by the liner, suggesting that Friday’s route had deviated far from its usual course.
Worries are growing that the ship could cause an environmental disaster if it breaks up and sheds its fuel.
Costa Concordia had just left the port of Civitavecchia, north of Rome, carrying roughly 2,300 tons of fuel for a week-long Mediterranean cruise when it crashed.
The area where the ship capsized is a maritime park famous for its pristine waters, varied marine life and coral.
Italian Environment Minister Corrado Clini said there was evidence that liquid was leaking from the ship, but he could not confirm whether the fluid was fuel.
Corrado Clini said the government would declare a state of emergency to release extra funding to help avoid a fuel spill causing an environmental disaster.