Breivik had sued the Norwegian authorities, claiming his conditions were "inhumane" and he was suicidal.

But a court ruled on Thursday that Breivik's sentencing terms were "not a violation of human rights".

Breivik's lawyer said his client was disappointed with the outcome and would appeal against the latest judgment.

He has been held in isolation ever since he killed eight people with a car bomb and shot dead another 69, most of them teenagers, at a summer youth camp on the island of Utoeya on 22 July 2011.

He is currently serving a 21-year sentence, the maximum a court in Norway can impose, though it can be extended for as long as he is deemed a threat.

His lawyers claimed he had been living in a "completely locked world" and did "not wish to be alive any more". They had asked the court to lift restrictions on his correspondence with the outside world.

But judges at the Oslo District Court on Thursday said the restrictions placed on Breivik's communications were justified because he remained a danger to society.

They ruled that he enjoyed "relatively great freedom" at the facility and had access to many services in his everyday life.

"He studies and works on his political projects," the verdict said.

Oeystein Storrvi, Breivik's lawyer, told Reuters: "He has been in isolation for 12 years and easing of his conditions is vital for his wellbeing in the prison."

Breivik cried during his testimony in January, claiming he was sorry for the attack and that his life had become a nightmare that had left him suicidal.

But the following day, a psychologist told the court that she did not consider him to be depressed and there was a "low risk" of suicide.

Now aged 45, Breivik currently spends his time in a dedicated section of Ringerike prison - located on the shores of the lake that surrounds Utoeya.

At the prison, Breivik has access to a training room, kitchen, TV room and a bathroom.

Many of those killed on the island were teenagers involved with the Norwegian Labour Party's youth wing, the AUF. The attacks remain Norway's worst peacetime atrocity.

Breivik has challenged the terms of his sentence before, winning part of his human rights case against the Norwegian state in 2016 before it was overturned the following year.

He unsuccessfully applied for parole in 2022, with the court ruling he had not changed and remained a risk to society.

By James Gregory