Danish inventor Peter Madsen has admitted dismembering journalist Kim Wall but denies killing her – and has made a bizarre new claim as to how she died.

Madsen is accused of killing the Swedish reporter, whose headless and limbless torso was found in waters off Copenhagen 11 days after she went missing.

The 46-year-old inventor has now told police he was involved in mutilating Wall's body, but was not responsible for her death. He now says she died from carbon monoxide poisoning inside the submarine while he was on the deck of the vessel, Danish police revealed in a statement.

Madsen previously claimed Wall died after she accidentally hit her head on one of the submarine's hatches before he attempted to dispose of her body.

An autopsy revealed no sign of fracture on Wall's skull or any sign of other blunt violence to the skull. A post-mortem stated that she had suffered knife wounds to her genitals and ribcage.

Madsen had arranged to be interviewed by Walls on his homemade submarine on 10 August. She was reported missing the next day.

Prosecutors allege that Madsen killinged the journalist while she was on-board the vessel and then deliberately sank it when the search for the 30-year-old commenced.

He is accused of murdering Wall in a sexually motivated attack. A hard disk containing fetish films of women being burned, decapitated and tortured was previously recovered from Madsen's workshop, according to prosecutors.

Wall's head, legs and clothing were eventually found in weighed-down bags by police divers on 6 October.

 Danish submarine owner and inventor Peter Madsen talks to Danish police in Dragor Harbor south of Copenhagen, Denmark
Peter Madsen talks to Danish police in Dragor Harbor south of Copenhagen, Denmark Reuters