Norway's government on Tuesday filed an appeal against the Oslo district court's ruling that Norwegian authorities had violated the human rights of mass killer Anders Behring Breivik.

Justice Minister Anders Anundsen says the government disagrees with the April 20 ruling that said the isolation of Breivik, who is in prison for killing 77 people in a bomb-and-gun massacre in 2011, breaches the European Convention on Human Rights.

"I have today asked the Office of the Attorney General to appeal the verdict," Anundsen said in a statement. He added further details about the government's decision would be released within days.

Breivik, 37, sued the government last month saying his isolation from other prisoners, frequent strip searches and the fact that he was often handcuffed during the early part of his incarceration violated his human rights. He is held in solitary confinement in a three-cell complex where he can play video games, watch TV and exercise.

During a four-day hearing at Skien prison in southern Norway, where Breivik is serving his sentence, he also complained about the quality of the prison food, having to eat with plastic utensils and not being able to communicate with sympathizers.

The government rejected his complaints, saying he was treated humanely despite the severity of his crimes and that he must be separated from other inmates for safety reasons.

"The prohibition of inhuman and degrading treatment represents a fundamental value in a democratic society," the court said in its ruling. "This applies no matter what — also in the treatment of terrorists and killers."

It also ordered the government to pay Breivik's legal costs of 331,000 kroner (about $52,000 Cdn). However, it dismissed Breivik's claim that his right to respect for private and family life was violated by restrictions on contacts with other right-wing extremists.