Anders Behring Breivik, the man accused of killing 77 people in a bomb and gun rampage in Norway last summer admitted that he had committed the acts but said he was not guilty.
According to media reports, he has claimed that he was doing it in self-defense and the court recorded a plea of not guilty for him.
As his trial opened earlier in the day, he raised a clenched fist and said he did not recognize the authority of the court.
According to the Norwegian media, he objected to the judge's friendship with a former justice minister, calling the trial political.
He then listened impassively as prosecutor Inga Bejer Engh read the charges against him, describing how dozens of teenagers and young people died from shots to the head and body.
Breivik, in a black suit and jawline beard, read the indictment as the prosecutor spoke, showing no reaction as she listed the injuries the victims suffered on Utoya Island.
Breivik claims the shooting rampage was meant to save Norway from being taken over by multicultural and Muslim forces and to prevent ethnic cleansing of Norwegians.