SKIEN, NORWAY (AFP) - Mass murderer Anders Behring Breivik made a Nazi salute on Tuesday (March 15) as he arrived in court for his lawsuit against the Norwegian state, which he accuses of violating his human rights by holding him in isolation.

Sporting a shaved head and a dark suit with a white shirt, Breivik turned toward the media present in the courtroom and extended his right arm.

Prior to the proceedings, several victims had expressed fears the hearings would give the killer a platform for his rightwing extremist ideology.

Breivik is serving a maximum 21-year sentence for killing eight people in a bomb attack outside a government building in Oslo in July 2011, then murdering another 69 people, most of them teenagers, in a rampage at a Labour Youth camp on the island of Utoya.

His prison sentence can be extended if he is still considered a danger to society.

The 37-year-old has sued the state for breaching two clauses of the European Convention on Human Rights, one which prohibits "inhuman or degrading treatment or punishment", and one which guarantees the right of respect for "private and family life" and "correspondence".

Since his arrest on July 22, 2011, Breivik has been held apart from the rest of the prison population and his contacts with the outside world strictly controlled.

Prison officials censor his mail to prevent him from establishing an "extremist network", according to authorities, and his rare visits are almost exclusively with professionals behind a glass partition.

After making his salute in a makeshift courtroom set up in the gymnasium of the Skien prison where he is being held, Breivik, seated between his lawyers, closely examined the faces of all those people present.

On several occasions during his 2012 trial, he made a variation of the Nazi salute by holding his closed right fist to his heart and then extending his arm.

In a letter to AFP dated October 27, 2014, he described himself as a "militant nationalist" and pledged his "allegiance to national socialism".

In his opening remarks on Tuesday, Breivik's lawyer Oystein Storrvik stressed that his conditions were of particular importance given that he will probably spend "his whole life in prison." Storrvik has previously told AFP he was willing to take the case as far as the European Court of Human Rights in Strasbourg.

Breivik has in the past likened his prison conditions to "torture". He is suffering "clear damage" from his isolation, according to Storrvik.

The office of the attorney general, however, has insisted that his conditions are "well within the limits of what is permitted" under the Convention.

He has access to three cells - one for living, one for studying and a third for physical exercise - as well as a television, a computer without Internet access and a game console. He is able to prepare his own food and do his own laundry.

"There are limits to his contacts with the outside world which are of course strict... but he is not totally excluded from all contact with other people," the lawyer defending the state at trial, Marius Emberland, told AFP prior to the proceedings, citing Breivik's contact with penitentiary staff.

In November, Norway's human rights pointman said Breivik's prison regimen represented "an elevated risk of inhumane treatment".

But according to public broadcaster NRK, doctors who monitor him in prison are expected to testify that he is not suffering from his conditions.

For security reasons the proceedings are being held at the Skien prison, about 130km south-west of Oslo.

Desks and chairs were set up in the makeshift courtroom, the coloured lines and floor markings still visible, as well as a climbing wall, two basketball hoops and exercise bars.

The proceedings, which will last until Friday, are being broadcast on Norwegian television, though Breivik's own testimony on Wednesday morning will not be aired out of respect for the victims.

Seen as a test of Norway's legal system, the case may reopen painful wounds for victims' families in a country that has tried hard to forget the perpetrator of the country's deadliest attacks since World War II.

Breivik "got what he wanted", Utoya survivor Viljar Hanssen tweeted on Monday.

"He is adored in extreme-right circles and can spread hate from his cell." Breivik shot Hanssen four times, including one bullet to the head.

"Proud and happy however to live in a robust state of law that applies to everyone. It's the cornerstone of a modern democracy," he wrote.