Self Confessed mass killer Anders Behring Breivik returned to the witness stand on Friday on the fifth day of his criminal trial for killing 77 people.

He entered the Oslo district court without making the clenched-fist salute he had used on the first three days of the trial - which the survivors and bereaved families had found upsetting.

Lawyers have warned that his evidence today will be "the most difficult" heard so far in the trial. As he will give detailed evidence about his research into bomb making and his bomb factory. Under questioning, the court asked how he felt planning the bombs and its effect on his victims, he replied that he had to undergo a complete dehumanisation programme to carry out these acts and that under normal circumstances he was a nice person.

Breivik's evidence is scheduled to last five days, concluding on Monday. The entire proceedings are expected to last 10 weeks.