Rescue crews have blasted holes in a stricken cruise ship in order to gain easier access as hopes fade of finding survivors among the 29 people missing.
Six people are known to have died after the Costa Concordia crashed into rocks off Italy's west coast on Friday night.
The ship's owners have blamed the captain for Friday's crash, saying he changed course towards an island.
Capt Francesco Schettino has been detained on suspicion of manslaughter and is due to appear shortly in court.
Capt Schettino, 52, has also been accused of abandoning his vessel before all the passengers had been evacuated.
He is to answer questions from a magistrate who will decide if he is to remain in custody.
Italian media have released a recording of a conversation between Capt Schettino and a coast guard official that casts doubt on the caption's statement that he stayed on the Costa Concordia until all the passengers were evacuated.
Meanwhile, as the rescue operation continues, plans are being made to remove the vessel's fuel oil before it leaks out and damages a maritime preserve.
The ship is said to be stable after it shifted on Monday, putting a halt to the search for several hours.
Dutch salvage firm Smit, hired by Costa Cruises to remove the fuel, said the operation would take two to four weeks.
A man involved with the salvage operation told the BBC they hoped to begin pumping by Thursday or Friday.
Meanwhile, Italian officials have denied a newspaper report that a seventh body had been found overnight on the vessel.
Captain 'in difficult position'
Shortly after daybreak on Tuesday rescue crews blasted several holes in the ship, now lying on its side metres from Giglio island, off the Tuscan coast, in order to gain access to areas they have not been able to search.
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 Capt Schettino hit the rocks because he deliberately steered the ship towards Giglio Island.
Prosecutors also claim that he was responsible for the disaster. They say the captain wanted to make a close pass of Giglio in order to "salute" a crew member's family who live there.
"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.
Italian media have released what they say is a conversation between the captain and the coast guard, apparently drawn from one of the ship's "black box" recorders.
- Divers describe scene in cruise liner 03:26
- Aerial video shows gash in hull 00:38
- Captain: Rocks not detected 01:07
- Explosives used in search for missing 01:43
- Why the captain changed course 02:04
- How cruise ship deviated from route 03:15
- Night vision footage of ship rescue 04:18
- Cruise ship dancer: 'Absolute panic' 04:21
The conversation suggests Capt Schettino left the ship before all the passengers had been evacuated, contradicting a statement he gave later to Italian TV.
"Now you go to the bow, you climb up the emergency ladder and co-ordinate the evacuation," a coast guard official tells him.
"You must tell us how many people, children, women and passengers are there and the exact number of each category."
And then: "What are you doing? Are you abandoning the rescue? Captain, this is an order, I am the one in charge now. You have declared abandoning ship... There are already bodies."
Capt 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.
The ship, carrying 4,200 passengers and crew, had its hull ripped through when it hit rocks late on Friday, just hours after leaving the port of Civitavecchia for a week-long Mediterranean cruise.
Some people were forced to swim for land as the angle of the ship made boarding lifeboats impossible. Dramatic infrared footage taken from a helicopter shows lines of people climbing ropes down the exposed hull of the vessel to reach rescue boats on the water.
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.
Rodolfo Raiteri, head of the coast guard'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.
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.
Meanwhile, the shipping newspaper Lloyd's List said it had been able to trace the course of the 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.