The Italian coast guard said two more bodies have been recovered following a blaze on the Norman Atlantic, which was sailing from the western Greek port of Patras to Ancona in Italy.
Four bodies were discovered in the water around the ferry today and yesterday a Greek man was found dead in a lifeboat chute.
All passengers have now been evacuated from the stricken vessel, authorities said, with 414 rescued.
Six Britons were among those aboard the ferry, which an inspection just 10 days ago found had serious deficiencies.
It is not believed any Britons are among the dead.
The vessel, operated by Greek shipping company Anek Lines, was found to have failings with fire safety and its plans for how to handle passengers in the event of an emergency.
Among those saved were British showjumper Nick Channing-Williams, who was reunited with his Greek fiancee Regina Theoffili after they were rescued separately from the blazing vessel.
A photograph sent to his family by a member of the Italian air force shows a grinning Mr Channing-Williams covered in black soot and oil after he spent more than a day trying to avoid acrid fumes.
Mr Channing-Williams said he and other passengers tried to tie a tow rope from tug boats on to the front of the ferry but gave up after it repeatedly snapped.
He told Sky News there were moments when he was “absolutely terrified” and did not think he would live through it.
Speaking after being reunited with Ms Theoffili, he said: “That was quite an emotional reunion because we were separated for a few hours which was not very nice and in the early hours of this morning I was starting to question whether we were going to get off it or not.”
Rescue helicopters braved high winds and treacherous seas to pluck hundreds of passengers to safety.
The blaze is believed to have broken out early yesterday morning on one of the ferry’s car decks.
Mr Channing-Williams, 37, who was travelling to see his family in Berkshire for New Year and was lifted to safety, said there were times when he thought he would not make it off the ferry alive.
He said: “When the flames are licking up around the boat and there is just no sign of help and they are talking about sending a boat that is going to be four hours away, you feel somewhat helpless...
“Around 5 o’clock this morning I did send a couple of text messages out to people because I sort of had convinced myself that we were going a little bit the wrong way.”
The first sign of a problem was at 5am yesterday when a fire alarm sounded, he said.
By the time he reached the deck “the flames were huge, and all the cars were on fire”.
He said: “It was actually very scary, to be honest. There was only one place you could stand, which was in the rain.”
Mr Channing-Williams and his fiancee spent hours standing on the deck in rain, thunder and lightning as the blaze raged.
By the evening passengers were panicking as the ferry began to list and the heat intensified.
He said: “The fire was basically cooking everybody’s feet and everyone was in a queue to get on a lifeboat. With the heat just being so enormous, people just panicked. I didn’t even try and get on one. Regina and I were stood upstairs and just hoped for the best, really, that someone would come and help us.”
Mr Channing-Williams said he spent the night at the front of the ferry with other people after climbing down a rope to try to help tie lines from a tug boat.
At one point they were trapped when flames blocked their path.
He said: “It was something interesting. We ended up with three attempts, and after the third time of the rope snapping on us, that was when we gave up.
“We ended up climbing back up a rope through one of the windows of the ferry and we got back up to where they were evacuating with a helicopter.”
Mr Channing-Williams said he saw other terrified families shivering and shaking in the rain and cold as, like him, they had not had the chance to gather suitable clothing.
And he said his fiancee saw one man slip to his death earlier today.
He said: “There was a chap this morning that Regina witnessed slipping off the bottom rung of the ladder and he went under the boat, and he also certainly didn’t make it either.”
Mr Channing-Williams described the ferry’s captain and crew as “very helpful” during the incident.