Norwegian authorities are to appeal against a ruling that the human rights of mass murderer Anders Breivik have been violated by the conditions of his imprisonment, justice minister Anders Anundsen announced on Tuesday (26 April).

Earlier in April a court in Oslo ruled that the conditions of Breivik's imprisonment constituted an infringement of his human rights, and described his solitary confinement as a "completely locked world."

"I have asked the Office of the Attorney General to appeal the verdict," Anundsen said in a statement, and said the state did not agree that conditions constitute "inhuman or degrading" treatment, under article 3 of the European Convention on Human Rights.

Far-right extremist Breivik killed eight people in a bomb attack in the Norwegian capital, before shooting dead 69 people at a Labour party youth camp on the island of Utoeya in July 2011.

Breivik had challenged the government over the conditions of his confinement, under which he is kept alone in his cell for 22 to 23 hours a day, denied contact with other prisoners, and communicates with prison staff through a thick glass partition.

Judge Helen Andenaes Sekulic said in her ruling that the conditions of imprisonment were so markedly different from those of other inmates in Norway that they constituted an extra punishment. She said the right to humane conditions of imprisonment constituted a "a fundamental value in a democratic society" and also applied to "terrorists and killers."

Judge Sekulic said that Breivik had been woken up every hour at night, and had been subjected to strip searches with female officers present, which he found particularly difficult.

However she found that the state was right to restrict his correspondence, which she said did not violate his right to private or family life. Norwegian authorities say the condition is necessary to stop Breivik forming far-right networks outside prison.