Rudolf Mayer says his client should be in a psychiatric unit rather than facing a trial, which will not be fair because of press coverage of the case.

In a television interview for the Associated Press, Mr Fritzl's sister-in-law, identified only as Christine R, describes Mr Fritzl as a tyrant and said "I believe he spent a year and half in prison" for the conviction.

Police have declined to comment on the allegations, saying records that old would have been erased under Austria's statutes of limitation.

Under Austrian law convictions can be expunged after as little as five years.

Mr Mayer has said that if, in his opinion, a psychiatric evaluation of Mr Fritzl ordered by the court does not give a proper assessment of his client he will consider ordering a separate report himself.