Norway killer Breivik says solitary confinement 'further radicalised' him
Norwegian mass murderer Anders Behring Breivik has said that more than five years of prison isolation have further radicalised him.
He appeared at a court hearing at which the state is appealing against a finding that some of his treatment in prison amounted to "inhuman or degrading treatment or punishment".
Prosecutors had earlier warned that the right-wing extremist was more radical than ever.
Breivik killed 77 people in July 2011.
He murdered 69 people at a summer camp for young centre-left political activists on the island of Utoeya after, earlier in the day, setting off a car bomb in the capital Oslo, killing eight people.
The 37-year-old has been kept in solitary confinement since shortly after his arrest. In 2012, he was sentenced to 21 years in prison. In his three-cell complex, he can play video games, watch TV and exercise.
But he argues that being kept away from other prisoners for 22 to 23 hours a day breaches his human rights.
"I've become more radical. I was radical to start but these past five years I've become much more radical," he said as he gave evidence against the state.
"I'm seriously affected by the isolation, and radicalisation is perhaps the most serious effect of my isolation."
Breivik's lawyer Oystein Storrvik has said the killer is "mentally vulnerable" because of his prison conditions.
In April 2016, a Norwegian court upheld part of his claim, although it dismissed his argument that his right to respect for private and family life was violated by restrictions on contact with other right-wing extremists.
On Tuesday, the Norwegian government, which was also ordered to pay Breivik's legal costs of 330,000 kroner ($38,500; £31,600), began the process of appealing against the court's ruling.
The state says his prison conditions are better than those of most other prisoners to compensate for being kept in solitary confinement.
Prosecutor Fredrik Sejersted rejected the assertion that his human rights were being violated, and said Breivik was "even more convinced in his extreme far-right beliefs".
Reacting to Thursday's hearing, Mr Sejersted told Reuters news agency: "He's saying what is rational for him to say in the circumstances."
A verdict in the case is due in February.