The captain of the wrecked cruise ship which hit rocks off Italy made "an unapproved, unauthorised" deviation to his route, the liner's owners have said.

As the death toll in the disaster rose to six, Costa Cruises' chairman Pier Luigi Foschi apologised for the tragedy which has left dozens of people injured and the 114,000-tonne Costa Concordia lying on its side off Tuscany.

At the centre of the investigation into the disaster is the liner's captain, Francesco Schettino who, according to reports, was "showing off" and sailed as close to land as he did as he wanted to salute to a friend on shore.

He faces accusations that he abandoned the vessel before ensuring that all of the 4,200 people aboard, including 35 Britons, were safely evacuated.

Clarence Mitchell, who is representing Costa Cruises, said: "Mr Foschi confirmed the captain had been approaching the island of Giglio to 'make a salute'.

"The company says this (incident) was caused by an attempt by the captain to show the ship to the port.

"But there's a criminal investigation going on and we're not going to say anything that's going to compromise that or the captain's case."

While British survivors told of the panic on board after the ship began to list, Mr Foschi said the liner had passed all safety and technical tests in its 2011 evaluation.

The ships' masters' union Nautilus said vessels of the size of the Costa Concordia were "inherently unstable".

But the UK Chamber of Shipping and the European Cruise Council said such ships met stringent safety regulations which had recently been tightened.

James Thomas, 19, from Sutton Coldfield, Birmingham, a dancer who helped to direct petrified passengers off the vessel, said the instruction to abandon ship should have been given "an hour earlier, if not more".

Explaining that the ship was "ultra safe", Mr Foschi said the captain had made an unauthorised and unapproved deviation from the ship's programmed course.

Mr Foschi said: "This route was put in correctly. The fact that it left from this course is due solely to a manoeuvre by the commander that was unapproved, unauthorised and unknown to Costa."

Mr Foschi added: "Personally and on behalf of the Costa Crociere (Cruises) I want to say we are very sorry for this tragic accident that's happened."

Capt Schettino, who has commanded the ship since it was built in 2006, has said he is not to blame and that nautical charts did not show the rocks off the tiny island of Giglio.

Mr Thomas said people on board "knew something was deadly wrong" when the ship began to tilt.

He went on: "We knew we were going to have to do something drastic to get out of the situation we were in. Even if it was 'just in case' it (the call to abandon ship) should have been called an hour earlier, if not more."

Mr Thomas added: "All I came off with was wet trousers and wet shoes, luckily without any injuries.

"But I saw people with some horrific injuries and that is one thing which I am never going to be able to get out of my head which is the worst thing.

Another survivor, Rose Metcalf, 23, from Wimborne in Dorset, said: "There was absolute panic. It was just terrifying, it was a case of just trying to keep people calm. People were white, people were crying, screaming."

The body of a sixth victim of the tragedy has been found on the ship.

The search for any survivors continued until it had to be suspended in early afternoon after the vessel shifted a few inches in rough seas. Later, with the weather improving, the search resumed.

Costa Cruises are also concerned about the 500,000 gallons of fuel on board which are in 17 separate tanks.

Allan Graveson, senior national secretary of the ships' masters' union, Nautilus, said large liners such as the Costa Concordia were "inherently unstable".

Operators of such ships were "putting profits before safety" and loading them with too many decks, he added.

But Robert Ashdown, the European Cruise Council's technical, environment and operations director, said Mr Graveson's view was "just not right" and big ships were "more stable than they have ever been".

And David Balston, the UK Chamber of Shipping's safety and environment director, said safety regulations were constantly updated to take account of large vessels.

Costa Cruises owner Carnival, the world's largest cruise operator, said the disaster would wipe £62 million from its profits this year.

Shares in the company fell 21% at one point.

Giglio Mayor Sergio Ortelli said hopes of finding any of the missing still alive were minimal, the Italian press reported.
He added that the only hope was that bubbles of air had formed within the ship.