Breivik detonated a bomb in Oslo in July 2011 that killed eight people.
Anders Breivik, the Norwegian mass killer, has lost his human rights case against the state after an appeal court overturned an earlier ruling that his solitary confinement was inhumane.
Strict conditions for Breivik, who has no contact with other inmates, were justified because he was unrepentant and posed a threat of violence, said a statement by the Borgarting appeal court.
Far-right terrorist Breivik has been kept in near-isolation in a three-room cell since he was found guilty of murdering 77 people in 2011 and was sentenced to 21 years in prison.
The 38-year-old neo-Nazi is now serving a 21-year-prison sentence for massacring 77 people in July 2011.
Breivik's lawyer Oeystein Storrvik expressed surprise at the verdict and said he would appeal to Norway's Supreme Court.
At a March 2016 hearing in the district court, Breivik had said he was feeling bad in jail, complained about cold coffee and grumbled that jail food was "worse than waterboarding".
The lower court judge noted in particular Breivik's lengthy isolation regime.
It heard that he was allowed visits from family and friends but the only person who had come was his mother, who has since died of cancer.
Breivik had also alleged that his private and family life were violated by the state - but those claims were struck down at the lower court previous year.
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