“I’m no monster,” Joself Fritzl was quoted as saying by his lawyer. He claimed credit for saving the life of his eldest daughter but added that he could have killed his daughter and all the children. “I could have killed them all. Then there would have been no trace. No-one would have found me out.”

In remarks transmitted by lawyer Rudolf Mayer to the newspaper, Fritzl, 73, said it was his act that saved the life of the eldest of the six surviving children born out of the sexual abuse.

Nineteen-year-old Kerstin, who was born in the cramped dungeon where Fritzl held his daughter prisoner, was rushed to hospital on April 19 with multiple organ failure. She has since been in an artificially-induced coma and put on a life-support machine.

Fritzl locked away his daughter Elisabeth, now 42, when she was just 18 and raped her, forcing to bear seven children in all.