Neo-Nazi mass murderer Anders Behring Breivik, who killed 77 people in 2011, will take his case over his "inhumane" prison conditions to the European Court of Human Rights, his lawyer said yesterday after exhausting all legal options in Norway.

Breivik, who for safety reasons has been held apart from other inmates since his arrest in 2011, has complained about his lengthy isolation. He wants the Norwegian state to be found guilty of violating the European Convention on Human Rights, which prohibits "inhumane" and "degrading" treatment. But Norway's highest court, the Supreme Court, yesterday refused to hear his case.

"None of the elements in the Breivik appeal have any chance of winning," the court said in a statement.

"Neither does the case raise any questions about the interpretation of the European Convention that haven't already been sufficiently clarified by the practices of the European Court of Human Rights," it added.

Breivik's lawyer argued that his extended isolation has been detrimental to his mental health.

Having exhausted his legal options in Norway, the rightwing extremist now plans to take his case to the Strasbourg court, his lawyer Oystein Storrvik said.

"We're going to take the case to Strasbourg as soon as possible," Breivik's lawyer Oystein Storrvik told AFP. "We've always been prepared for the possibility that our case before the Norwegian courts may not succeed."

The now 38-year-old inmate is serving a 21-year prison sentence that can be extended indefinitely.

In July 2011 Breivik, disguised as a police officer, tracked and gunned down 69 people, most of them teenagers, at a Labor Party youth camp on the island of Utoya, shortly after killing eight people in a bombing outside a government building in Oslo. He has never expressed any remorse for committing the worst atrocity in Norway's post-war history. He said he killed his victims because they embraced multiculturalism.

In prison, Breivik enjoys relatively comfortable material conditions, with three well-equipped cells. In April 2016, an Oslo district court stunned the survivors and families of the victims when it found the Norwegian state breached Breivik's rights, primarily by keeping him in lengthy isolation. That verdict was also a heavy blow to the Norwegian state, which prides itself of having a humane prison system.

But in March this year, the Oslo appeals court found that "Breivik is not, and has not, been subjected to torture or inhuman or degrading treatment." The state's lawyer had argued that Breivik was "a VIP inmate" who enjoyed "cosy" conditions, with cells that have views of nature outdoors and where he can exercise, play video games and watch television.

Yesterday's decision by the Supreme Court to refuse Breivik a new trial was met with relief in Norway, as the nation tries to turn the page on a painful chapter of its history. Each trial has caused repeated suffering for the survivors and families of the victims, especially since Breivik has used the court appearances as platforms to air his political ideology and provocations. Like the support group, many in Norway prefer not to mention Breivik by name, instead calling him "the terrorist", "the mass murderer", or "the child killer."