Rescuers were frantically searching for 15 people still missing from the wrecked cruise liner off Italy last night after managing to save two South Korean honeymooners and an Italian crewman earlier in the day.
Officials confirmed that another three bodies had been dragged from the water, bringing the death toll to six.
Foreign Secretary William Hague confirmed yesterday that all 35 Britons who had been on board were safe.
Prosecutor Francesco Verusio confirmed Francesco Schettino, captain of the Costa Concordia, was being questioned for alleged manslaughter, abandoning his ship while people were still aboard and causing a shipwreck.
The ship's operator, Costa Crociere, suggested the blame for the incident lay with Mr Schettino, saying in a statement that "preliminary indications" pointed to a "significant human error" on his part. The company addded:
"The route of the vessel appears to have been too close to the shore, and the captain's judgment in handling the emergency appears to have not followed standard Costa procedures."
Mr Schettino is understood to have claimed that rocks he struck off the island of Giglio while miles off course did not appear on charts – although the waters are well-charted.
One Giglio resident, Elena Ballerano, 32, said: "That explanation is ridiculous. Everyone who knows these waters in the slightest knows those rocks are there. The rescue wasn't very well done. But thank God it didn't happen out in open sea."
Costa Crociere denied some passengers' claims that Mr Schettino was in the boat's restaurant at the time of the accident. It insisted he was at the controls when the vessel hit a rocky outcrop off Giglio at about 9.30pm local time on Friday.
Mr Verusio appeared to accept that version of events but said the ship "was not on the right course". He added that the captain was on the bridge and was "therefore responsible for operations".
Italian rescuers continued to make forays into the 951ft vessel in the hope of finding other survivors. Three bodies – those of two French tourists and a Peruvian crew member – were recovered on Friday.
Last night, emergency teams warned that the search of the half-submerged ship was dangerous for divers because the decks were at almost a 90-degree angle and there was a risk the 114,500-tonne ship could slip off the rocks it had struck.
"This is a risky operation," coastguard commander Cosimo Nicastro said. "The ship is in waters that are [100ft] deep but it could slowly slip into the sea and sink completely."
The Costa Concordia had been carrying 3,206 passengers and 1,023 crew. Mr Verusio said its captain had "approached Giglio island in a very awkward way, hit a rock that stuck into its left side, making [the boat] list and take on a huge amount of water in the space of two or three minutes".
Prosecutors said the captain was on shore by about 11.40pm on Friday but the last passengers were not evacuated until 6am the following day. But in an interview with an Italian television channel, Mr Schettino claimed: "We were the last to leave the ship."
Yesterday it emerged that many of the waiting staff had stepped in to lead passengers off the stricken liner.
The disaster happened just hours after the ship left Civitavecchia near Rome at the start of a Mediterranean cruise that was meant to take it to Savona in north-west Italy and then to Marseille and Barcelona.
"There was panic immediately," said Francesca Sinatra, a passenger from Rome. "People were shouting and climbing on each other."
The lifeboat that she was in collided a number of times with the listing hull as it was lowered due to the angle, she added. The first alarm was sounded at 9.45pm and the "abandon ship" order given at 10.10pm as the vessel began to list rapidly with water gushing in through a 60-metre gash.
"We were lucky we were so close to the shore," said Jose Rodriguez, 43, a Honduran barman. "Thank God."
Investigators have begun to analyse the black box recovered by rescuers, which will have logged the ship's movements as well as conversations between personnel. But experts said it could be months before it became clear precisely what happened before and after the Costa Concordia crashed into the rocks.
The British ambassador in Rome visited the scene at the weekend along with diplomatic officials from more than a dozen countries. Some have been privately critical of the handling of the ship's evacuation and a lack of information about their citizens.
At least 42 people were injured, two seriously – a woman with a blow to the head and a man struck in the spine.
Cruising: The figures
190 million people took a cruise worldwide between 1980 and 2010 of which 67 per cent were in the past decade. In the early 1970s 500,000 people took cruises.
The total worldwide cruise industry is estimated to be worth £34bn
Average capacity for ships in the 1990s was 1,600. By 2010 it had climbed to 3,000