Berlin: A man described as a "cold sadist" imprisoned a woman in his homemade torture chamber rigged with eight bombs designed to detonate when he had finished with her.

Thomas Fischer, 30, turned his tiny flat into a terrifying lair in which he had installed an old soundproofed telephone box to lock up his victim.

He used an assortment of scalpels, needles and syringes to practice with on a mannequin before snatching the woman off a street in Hamburg.

But while it appeared he had been planning to imprison her for a number of months, she was only in his clutches for two hours after he forgot to lock the door to the ‘cell.'

The 26-year-old victim, who was handcuffed, managed to flee by lunging through a window of the ground-floor flat.

Fischer tore into the street after her but she outran him and fled to the safety of a friend's home.

She brought police to the apartment, where Fischer had returned. He has not said a word since his arrest. Police searching the flat were said to be left speechless by the macabre set-up.

The outside of the windows were criss-crossed with barbed wire and sealed on the inside with baking foil and clingfilm. A hand grenade and Walther pistol were also found.

The cupboards were stocked with tinned food, rice and pasta as ‘if he was prepared for a long time indoors.'

Evacuation

The fertiliser-based bombs, which were packed into fire extinguishers, were so volatile police had to evacuate surrounding buildings with 300 residents when his flat was searched.

Fischer had apparently made them using recipes he found on the internet.

Police said he and the woman knew each other after being introduced by a friend, but there was "definitely no relationship" and that Fischer had become obsessed with "owning" her and stalked her. Some media reports said he wanted to get her pregnant after kidnapping her on Friday.