Fritzl locked up his mother until she died

Josef Fritzl admitted locking up his mother until her death in the same house where he later imprisoned his daughter and the seven children he fathered with her, London's Telegraph reports.

The 42-year-old Austrian made the claims to a psychologist preparing a report on his mental state ahead of his trial in February, the paper stated.

"I locked [my mother] up in a room at the top of the house," Fritzl said in the leaked psychologist's report. "I then bricked in the window so that she never again saw the light of day."

Fritzl told neighbours that his mother died around the time he took ownership of her home in 1959, but an Austrian newspaper claims she did not die until 1980, suggesting that she could have spent 21 years in the locked bedroom.

It emerged in April that Fritzl has kept his daughter, Elisabeth, locked up in a purpose-built room in the town of Amstetten where he sexually abused her across 24 years, the paper stated.

But the paper states that Fritzl's friends have expressed doubt that he could have also kept his mother hidden in the house for so long.

The 73-year-old told the psychologist that he wanted to punish his mother for his loveless, brutal childhood.

"She used to beat me, hit me until I was lying in a pool of blood on the floor. It left me feeling totally humiliated and weak," he said.

"My mother was a servant and she used to work hard all her life, I never had a kiss from her, I was never cuddled although I wanted it - I wanted that she would be good to me. But the only thing she ever did with me was to go to the church."

The revelations are contained in a 130-page report compiled during six interview sessions by Dr Adelheid Kastner of the Wagner-Jauregg mental asylum in Linz.

When asked if this had played a part in his decision to lock up his daughter, Fritzl is quoted as replying: "To be honest I just didn't think about it, about her being my daughter, I saw her as my wife and as my partner."

Fritzl also told the psychologist that he was "born to be a rapist". Dr Kastner advised that he is not insane, but is a danger to the public and should never be released from prison.

Charges against Fritzl are yet to be finalised.