The Danish inventor arrested in connection with the disappearance of a Swedish journalist last seen on his home-made submarine has admitted she died on the vessel, police say today.

Peter Madsen, 46, claims 30-year-old Kim Wall died in an accident on his submarine, and that he then buried her at sea in a bay near Copenhagen.

Danish and Swedish authorities have been combing the waters along their respective coasts for ten days in the search for Miss Wall's remains, and it is hoped the new revelations can speed up the search.

Dead: Kim Wall, 30, (left) had gone along for the submarine's voyage to report on Peter Madsen (right), who has now admitted to 'burying her at sea' after she died on the vessel

Last moments: One of the last images taken of Miss Wall shows her on board the sub alongside Madsen on Thursday August 10

'The accused has told police and the court that an accident happened on board the submarine, which caused the death of Kim Wall, and that he after this buried her at sea at an undefined place in Køge Bay,' Copenhagen authorities said in a statement on Monday.

'Copenhagen Police adds that the man is still held on suspicion of aggravated manslaughter.'

Miss Wall was last seen on board the vessel with amateur builder Madsen on August 10, but until now, he has insisted he let her off that evening.

Madsen was picked up by the Danish navy on August 11, when his submarine sunk in Copenhagen harbour.

He was photographer making a 'thumbs up' as he made it to the shore, but was later arrested after Miss Wall's family reported her missing.

Danish investigators say they have found evidence the Nautilus was sunk deliberately.

Tragedy: Journalist Kim Wall died on the submarine, Madsen has admitted, but he claims it was an accident

Mystery: Danish police enlisted the help of their Swedish counterparts, and will continue the search for Miss Wall's body

Extended search: A Swedish Sea Rescue Society unit searches for the remains of Kim Wall at Lundakra Bay between Barseback and Landskrona, in Sweden, last week

'Hot-tempered': Peter Madsen, pictured with fellow enthusiast Kristian von Bengtson and one of their rocket prototypes in 2010, allegedly has a history of lashing out at journalists

Miss Wall was a freelance journalist who graduated with a masters from Columbia University before going on to write about identity, gender, pop-culture, social justice and foreign policy.

She grew up in Sweden but spent time living in New York and Beijing. Her writing has appeared in Harpers, The Guardian, New York Times, Foreign Policy, Vice Magazine, Slate, South China Morning Post, The Atlantic, Roads & Kingdoms, and TIME.

The freelance reporter boarded the sub, which was built by Madsen, on the evening of Thursday 10th August in order to write a story about the inventor.

On Friday morning the Danish Navy were scrambled to help the stricken sub, before reporting it sunk at 10.45am.

Madsen claims he was the only one on board at the time, and that he dropped Miss Wall off at the mouth of the harbour shortly after 10pm the previous night.

But Danish police on Sunday said he has given them several conflicting accounts of what had happened, without elaborating further.

Passionate: Madsen's biographer has revealed that the hobby rocket builder has made enemies of the people he has worked with , and that his temper can flare unexpectantly

Police raised the wreckage of UC3 Nautilus two days after it went down, but failed to find a body or any other signs of Miss Wall

Around the time he claimed to have dropped Miss Wall off, Madsen sent a mysterious text to a friend saying she had left the vessel and cancelling a trip he was supposed to be taking on the submarine the following day, according to local reports.

He did not respond to questions from the friend about why he had dropped Miss Wall off or why the trip was being cancelled.

Madsen was arrested on manslaughter charges the following Saturday before a judge ordered that he be held in custody while investigations are carried out.

He is charged with having killed Miss Wall 'in an unknown way and in an unknown place sometime after 5pm on Thursday.'

Before the first court hearing, which was held in private and attended by his relatives, Madsen smiled, and chatted with both his lawyer and reporters.

If convicted, Madsen faces between five years and life in prison.

Madsen, an amateur enthusiast who had built the UC3 Nautilus himself, has a history of lashing out at journalists who gave his project bad press, his biographer has said.

‘He often ends up in conflicts, and has a lot of enemies,' says Thomas Djursing, a journalist who has written a book about Madsen.

'He can throw tools at you. But at the same time, he's not a violent person. I've never been afraid of him,' he told Aftonbladet.

Mr Djursing adds that Madsen would often become angry with journalists who wrote about his ambitious projects in a negative way, and says 'I don't know a journalist who has not been in conflict with him'.

In Mr Djursing's book 'Rocket Madsen', the inventor describes himself as a 'nerd with few friends' who grew up with his elderly father after the parents separation.

The UC3 Nautilus was raised from the bottom of Copenhagen harbour where it had been under 8m (24ft) of water since sinking on Friday morning

Despite not finding Miss Wall's body, Danish investigators are continuing to search in water and on land for any sign of her

Police technicians are pictured investigating the rescued private owned submarine UC3 Nautilus today

Madsen claims he dropped Miss Wall off at the mouth of the harbour and was the only one on board when his craft (pictured right) sank

The 40-ton, 18-meter long Nautilus, one of three subs built by Madsen, was found by divers under 7m (24ft) of water, though they were unable to enter it safely

Early on, he joined several rocket and space travel clubs, but his lack of patience and short fuse saw him excluded from the societies in his teens.

'The past few years, he has been driven by a kind of vengeance. To show those he has worked with in the past, but who has since become his adversaries, that he can beat them,' Mr Djursing toldExpressen.

'He is a crazy person,' photographer Bo Tornvig tells the newspaper.

'I mean, making space rockets and sailing around in home-made submarines is not normal behaviour. But I've never seen him lay a hand on anyone. This whole story really stinks.

The 40-ton, 18-meter long Nautilus, one of three subs built by Madsen, was found by divers under 7m (24ft) of water, though they were unable to enter it safely.

A salvage ship, the Vina, has now raised the sub from the sea bed close to Copenhagen's south island of Dragoer and brought it back to shore to be inspected.

Kristian Isbak, who had responded to the Navy's call to help locate the ship, sailed out immediately Friday and saw Madsen standing wearing his trademark military fatigues in the submarine's tower while it was still afloat.

Divers had located the submarine underwater on Friday but were unable to enter it safely

The submarine was reported missing early on Friday by Miss Wall's boyfriend after she failed to return home, prompting a major search operation by the Danish Navy

Madsen, pictured above in 2008 in front of his submarine, was seen standing the tower of the still-floating submarine moments before it sank, according to a rescuer

Peter Madsen, who built the submarine himself before inviting Miss Wall along for the maiden voyage, is still under investigation for negligent manslaughter as investigators say there is evidence it was wrecked deliberately

'He then climbed down inside the submarine and there was then some kind of air flow coming up and the submarine started to sink,' Isbak told The Associated Press.

'(He) came up again and stayed in the tower until water came into it' before swimming to a nearby boat as the submarine sank, he added.

Madsen said there was a valve error that became serious when he tried to repair it.

Footage aired on Denmark's TV2 channel showed Madsen, 46, getting off what seemed to be a private boat and making a thumbs up sign as he walked away.

Upon his rescue from Køge Bay, Madsen said: 'I'm fine. But I'm sorry because 'Nautilus' has gone down.'

The submarine was Madsen's third attempt at building such a structure and was the largest privately built submarine in the world at the time of its launch.

The Nautilus was a diesel-electric submarine. The diesel engine is uses when sailing or propelling just below the surface, while the electrical engine is used when the submarine is deep below the water's surface.

It was built like a post-World War II submarine, with a galley, crew bunks, officer's mass, bridge and engine room.

It's named after the famed submarine manned by Jules Verne's Captain Nemo character in Twenty Thousand Leagues Under the Sea.