The man behind the massacre in Norway last year which left 77 people dead has told a court on Friday he was a "nice person" who had trained himself to stifle his emotions so he could carry out the shooting and bombing rampage.

Anders Behring Breivik, 33, admitted to killing eight people with a car bomb at the government's headquarters in Oslo, then gunning down 69 people, most of them teenagers, at a Labour Party summer camp on Utoeya island.

But he has pleaded not guilty, insisting he was defending the country against waves of Muslim immigration facilitated by the political left.