Oslo , Norway ( CNN ) -- A Norwegian court ordered Anders Behring Breivik , charged with killing 77 people last July , to undergo a month-long psychiatric evaluation as experts seek to determine his mental state ahead of a trial . Breivik is accused of killing eight people in a bomb attack in Oslo and 69 more in a gun rampage on nearby Utoya Island on July 22 . It was the deadliest attack on Norwegian soil since World War II . Two court-appointed psychiatric experts recommended that Breivik should spend four weeks under 24-hour psychiatric monitoring so the court can get the fullest possible picture of his behavior , according to court documents released Friday . He should be kept away from other patients but will still have to interact with psychiatric staff , the documents say . The observation will be carried out in facilities at Ila Prison , where he is being held . Breivik has said he will not cooperate with the two psychiatric experts , which underlines the need for constant observation , the court documents said . The two experts were appointed last month to evaluate his mental state after the court requested a second opinion because of the importance of the question of his sanity to Breivik 's trial . In November , prosecutors said psychiatrists had determined Breivik was paranoid and schizophrenic at the time of the attacks and during 13 interviews experts conducted with him afterward . Breivik has pleaded not guilty , though he has admitted carrying out the attacks , the judge handling his case said previously . It may not be possible for him to be sentenced to the maximum punishment for the crimes if he 's deemed insane . A court ruled Monday that Breivik can legally be kept in custody until his trial starts in April . Breivik reiterated some of his extremist views during Monday 's hearing , which began with him entering with a smile and offering up a raised , clenched-fist salute . Breivik says nobody could believe that he was insane , and describes questions about his mental condition as ridiculous , his lawyer , Geir Lippestad , told the court . Breivik claims the shooting rampage was a matter of self-defense , meant to save Norway from being taken over by multicultural forces and to prevent ethnic cleansing of Norwegians , Lippestad said . Authorities have described him as a right-wing Christian extremist . A 1,500-page manifesto attributed to Breivik posted on the Internet is critical of Muslim immigration and European liberalism , including Norway 's Labour Party . The victims on Utoya Island were among 700 mostly young people attending a Labour Party camp on the island . Breivik 's trial is scheduled to begin April 16 and is expected to last 10 weeks . Journalist Olav Mellingsaeter in Oslo contributed to this report .
He will be kept under 24-hour observation by mental health experts , a court ordered . He has said he will not cooperate with the psychiatrists . He is suspected of killing 77 people in a bomb attack and shooting rampage last year . Breivik says he is not insane and was trying to protect himself from multiculturalism .