Anders Behring Breivik's slaughter of 77 people, the biggest single act of terrorism in Norway since the Second World War, sent shockwaves through the country and throughout the wider world.

The sentence imposed by Oslo's district court brings to an end 13 months of anger and recrimination, with no-one able to comprehend how such a peaceful country could be engulfed in such horror.

During his trial, Breivik readily confessed to setting off a car bomb that killed eight people outside a government building in Oslo, before moving to the island of Utoya, where he shot dead another 69 people, mostly teenagers attending a Labour Party youth camp.

Despite the confession, Breivik pleaded not guilty to the charges. He refused to take criminal responsibility for the acts because, in his words, they were "based on goodness, not evil" and "cruel but necessary" to defend Norway against immigration and multiculturalism.

"[It was a ] small barbarian act to prevent a larger barbarian act," Breivik said.

He apologised for the innocent people he killed but restricted the scope of his apology to the bystanders "accidentally" killed by the car bomb, as they were not his targets.

He said he wanted hundreds to die in his attack at Utoya and hoped the Oslo bomb would kill all members of the Norwegian government.

Sane and accountable?

On the last day of the trial, in June, his defence lawyer asked him to be considered sane and accountable for his actions, as these were motivated by a political ideology.

He also asked for his client to be acquitted as Breivik believed the killings were justified.

The prosecution recommended the court to confine Breivik to psychiatric care instead.

"We are not convinced or certain that Breivik is legally insane but we are in doubt," said prosecutor Svein Holden.

Under Norwegian law, the maximum penalty for sane killers is 21 years' imprisonment. However, psychiatric sentences can vary considerably.

"We have murderers who have been sentenced to psychiatric care who will probably never get out again," said prosecutor Inga Bejer Engh.

Breivik told the court he would rather be executed than serve Norway's "pathetic" maximum punishment of 21 years.

"There are only two just and fair outcomes in this case: acquittal or capital punishment. I consider 21 years of prison as a pathetic punishment," he said.

Norway abolished the death penalty in peacetime in 1905.