That verdict would, the defence hope, lead to the massacre being described as politically motivated, whilst the prosecution are arguing that he is insane and should be in a psychiatric institution.

Mr Breivik has admitted murdering 77 people and injured 242 in July last year, when he bombed a government building in Oslo, and massacred teenage Labour Party supporters at a camp on the island of Utoeya.

Throughout the trial, Breivik has calmly justified his violent action as an attempt to halt what he saw as the “Islamisation” of Norway. His lawyer, Geir Lippestad, whilst condemning the actions, said his client was a political activist who was wholly aware of what he was doing.

He added that, before the events of July 22nd, Breivik had been a fairly ordinary young man with friends, not known for being a violent man. He argued that, had simple violence been his main justification, he would have taken a gun into the local shopping mall.

A support group for the injured and the families of those killed are planning to walk out of the courtroom when Breivik gives his closing statement.

Trond Blattmann, leader of the 22 July Support Group, told Reuters news agency: "For me the most important thing is that he [Breivik] is not going to be in Norwegian society anymore."

A verdict is not expected until later in the summer.