A court in Oslo on Wednesday partially upheld the claims of mass killer Anders Behring Breivik that he is subjected to prison conditions that violate his human rights.
"The prison conditions of Anders Behring Breivik represent an infringement of article three of the human rights convention," the court said, referring to law against inhumane treatment.
"This applies no matter what - also in the treatment of terrorists and killers," it added.
Breivik's attorney Oystein Storrvik said they would not appeal the ruling, which he said "supported what mattered to us - that his [Breivik's] isolation is a volation of his rights."
State attorney Marius Emberland expressed his "surprise" and said he disagreed with the court's decision. However, he wanted to study the ruling before deciding on whether to appeal.
The Norwegian right-wing extremist, who killed 77 people in 2011, had sued the state and prison authorities over restrictions he faces while serving his 21-year prison sentence for the attacks, considered the worst acts of violence in Norway since World War II.
He cited that five years of strip searches, censored mail and isolation in prison amount to "inhumane" treatment.
The court ruled in favour of Breivik over his complaints about time spent in isolation, the conditions and his limited ability to complain.
But Emberland told the NTB news agency that the court had not taken "sufficient account of compensatory measures the prison had taken" to improve the condictions Breivik served under.
The court did not agree with Breivik's claim that depriving him of contact with the outside world was a violation of his human rights.
The head of a support group for victims and next of kin of the attacks, Lisbeth Kristine Royneland, said she was "slightly disappointed" by the decision, but welcomed that Breivik was not allowed to freely disseminate his ideas as the court upheld the censorship of his mail.
"We will not appeal that decision," Storrvik said.
The state was also ordered to pay Breivik’s legal fees, estimated at 331,000 kroner (40,000 dollars).
The initial hearing, held a month ago at Skien prison, south of Oslo, was the first time Breivik was seen in public since his 2012 trial.
At the hearing, the state's attorneys argued that the stringent prison conditions were necessary as Breivik still poses a threat to society and visitors, citing testimony from prison wardens and a psychiatrist.
Breivik said the aim of his attacks was to punish the Labour Party, then in office, over its failure to stem the flow of Muslim immigrants to the country.