St Poelten, Austria - Josef Fritzl, the Austrian father who achieved worldwide notoriety in 2008 on allegations of incest with the daughter he kept locked up for 24 years, denied the murder charge brought against him at the start of his trial Monday in the Austrian town of St Poelten.

"Not guilty!" Fritzl responded to the charge of murder through negligence, relating to the death of a baby whom had been denied medical care in the cellar where he was keeping his daughter captive.

To the charges of incest and false imprisonment, Fritzl replied: "guilty." He said he was "partially guilty" of repeated rape, and rejected the charge of enslavement.

Fritzl is accused of having kept his daughter, Elisabeth, locked in the cellar of his house in Amstetten for 24 years, where he is said to have raped her several thousand times.

The daughter gave birth to seven children in the windowless dungeon, six of whom survived.

As the trial opened, Judge Andrea Humer told the court, "This is the deed of an individual perpetrator, not the crime of a whole town, or an entire nation."

At the time of Fritzl's arrest there had been media speculation about the degree to which family and neighbours might have realised something was amiss.

State prosecutor Christiane Burkheiser described to the jury the horrors of Fritzl's course of action.

He had kept his daughter Elisabeth chained up for months in the dark, windowless cellar, where he treated his daughter like a slave, Burkheiser told the court.

"She had to spend the first nine years confined to 18 square metres," the prosecution lawyer said. Only after the birth of the first children was her living space expanded by two tiny rooms, she added.

Burkheiser went into great detail about the infant who died in the cellar.

The baby, Michael, one of two twins, had suffered respiratory problems shortly after birth. Despite his daughter's pleading, Burkheiser said Fritzl had refused to seek medical aid.

The baby died within days, and Fritzl burnt the small body in a heating stove, the prosecution lawyer said.

Defence lawyer Rudolf Mayer was critical of media portrayals of his client. "Fritzl is no monster," he told the jury.

"The only extraordinary element to this case is the fact that someone built up a second family here," Mayer said. "If I only do this for the sex, I don't go making children," Fritzl's defence lawyer added.

Mayer also defended Fritzl's denial of the murder charge, saying that in the days following the baby's birth, Fritzl had "repeatedly gone into the cellar to check upon the child." 

"That's not the behaviour of someone committing murder," Mayer said.

If convicted of murder, Fritzl faces a lifelong prison sentence. The remaining charges would give him a maximum 15 years in prison.

Over the coming days, Elisabeth Fritzl is to testify via a pre- recorded 11-hour video statement, from which the public will be excluded, in order to protect the victims' privacy.

At the start of the hearing, the judge referred to the huge media interest the case had generated, adding that every defendant had the right "to a fair and independent trial."

In a pre-trial interview broadcast on German n-tv television, Mayer said he was hopeful that the jury could forget all that they had read about Fritzl in order to "follow the events of the trial without prejudice."

Fritzl entered the courtroom Monday, dressed in a light grey jacket and slate-coloured trousers. He kept his face shielded with a blue document folder, remaining silent while an Austrian journalist threw questions at the 73-year-old.

A courtroom reporter told n-tv that Fritzl avoided all eye contact with members of the public, keeping his face shielded until he was called to the witness stand, where he had his back to the public benches.

The trial has drawn 200 journalists from around the world to St Poelten, the capital of the province of Lower Austria, 60 kilometres from Amstetten.

Two hours into the hearings, media and members of the public were banned from the courtroom, to protect the privacy of the victims and the defendant as intimate details came to light.

British tabloid daily Sun was criticized in recent weeks for publishing photos of Fritzl's family out shopping. Elisabeth Fritzl, 43, has demanded that she and her children stay out of the media spotlight.

The family have since been moved to a nearby clinic, to maintain their privacy throughout the trial.

A verdict in the case is expected Friday.