Mass killer Anders Behring Breivik told a court on Wednesday he suffered degrading conditions in prison, including microwaved meals that were "worse than waterboarding", as he argued the Norwegian state had violated his human rights.

Breivik, who killed 77 people in a bombing and shooting rampage in 2011, said he found regular strip searches "bothersome and offensive" and felt isolated without visitors.

The hearing had heard on Tuesday he had his own treadmill, PlayStation, spin bicycle and reclinable chair with integrated foot stool, and took part in the prison's Christmas gingerbread-house baking contest. Lawyers for the government had said he also received newspapers, magazines, books, jigsaw puzzles, watched DVDs and listened to music on a Discman.

"The worst is isolation ... I am locked up 23 hours a day," Breivik said, answering questions from his lawyer, Oeystein Storrvik, before reading out a long written statement about his conditions.

He did not repeat a Nazi salute he made at the start of the four-day hearing, which had earned him a rebuke from judge Helen Andenaes Sekulic.

But he said he had been a follower of Nazism since his youth. "I have been a dedicated National Socialist since I was 12 ... I read (Adolf Hitler's book) Mein Kampf when I was 14 .... But I chose to keep it hidden."

People smiled and laughed in court when he complained about his microwaved meals.

Breivik argues he is the victim of inhuman and degrading treatment in violation of the European Convention on Human Rights, by being kept alone in a special three-room cell, with daily contact only with prison staff and professionals.

The state says the conditions are appropriate for a dangerous fanatic.

Wearing the same black suit, white shirt and golden tie he wore on the first day, Breivik will testify for roughly three hours in a lawsuit taking place in the gym hall of Skien prison, where Breivik is being held, in southern Norway.

Judge Sekulic told him she would intervene if his explanation strayed from his description of his prison conditions. There is no jury. When she asked his job description, Breivik said it was "party secretary of the Nordic State".

On the first day of the case, the state denied violating Breivik's human rights and said he had turned down offers to play chess with prison volunteers or bandy, a type of indoor hockey, with prison guards.

Defending the state, Adele Matheson Mestad argued that Breivik had received and sent about 4,000 letters, and only 15 per cent of them had been stopped by prison authorities. She said Breivik was trying to correspond with known Nazis and sympathisers. "Among them could be a new Breivik," she added.