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Norwegian police say the man in custody blamed for a bombing and shooting spree that killed at least 93 people has confessed to the crimes, but does not accept criminal responsibility.

The suspect, Anders Behring Breivik, 32, said he was motivated by a desire to bring about a revolution in Norwegian society, his lawyer said Sunday. A manifesto that he is believed to have written ranted against Muslim immigration to Europe and vowed revenge on "indigenous Europeans" who he accused of betraying their heritage.

Police labeled the attacks as acts of terrorism punishable by up to 21 years in prison according to Norwegian law, The Wall Street Journal reported. Norway does not have the death penalty.

Police said 85 people, many of them teenagers, were killed in the Friday afternoon shooting at a summer camp for the youth wing of the ruling Labor Party, on the island of Utoya.

The rampage followed a bombing 90 minutes earlier that ripped through government offices in the Norwegian capital and killed at least seven people.

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Geir Lippestad, Breivik's attorney, Saturday told Norway's NRK television network that his client had "admitted responsibility" for Friday's attacks.

"He explained that it was cruel but that he had to go through with these acts," Lippestad said, according to AFP, adding that the attacks were "apparently planned over a long period of time."

Lippestad said his client wanted to attack Norwegian society in order to change it.

He said his client would explain himself in court Monday when he was arraigned, the BBC reported. The court would determine if police could continue to hold him, the report said.

According to a 1500-page manifesto apparently written by Breivik, he had been planning the operation since at least autumn 2009.

The document -- entitled "2083-A European Declaration of Independence" -- was published on the site www.freak.no describing the author's background and political viewpoints.

It is part diary, part bomb-making manual and part political rant in which Breivik details his Islamophobia, attacks on Marxism and his initiation as a Knight Templar.

Dow Jones reported that several hours before the Oslo car bomb blast in a downtown government quarter, Breivik released a YouTube video calling for conservatives to "embrace martyrdom."

"[If] the multiculturalist elites of Europe continue to refuse to voluntarily transfer political and military power to our conservative revolutionary forces ... then [the second world war] is likely going to appear as a picnic compared to the coming carnage," the video stated in captions.

TV2 said sources within Norway's police confirmed the video was uploaded by Breivik, who apparently used the user name AndrewBreivik, an English translation of the name Anders Breivik.

Police Chief Sveinung Sponheim told a press conference Saturday that police were investigating unconfirmed witness reports of a second shooter on idyllic Utoya Island, where the gunman, disguised as a policeman, opened fire on terrified teenagers at a summer camp affiliated with the ruling Labour Party.

Sponheim said the suspect was answering questions and the interrogation was likely to continue for several days.

Police official Roger Andresen described him as a "Christian fundamentalist" who was "cooperating" with investigators in an attempt "to explain himself."

Police were also examining the suspect's car and computer records and hope to determine if he was affiliated with an extremist group.

As the questioning and search for an explanation went on, recovering any remaining bodies from the waters around the island of Utoya, some 25 miles northwest of Oslo, became a top priority.

Police said they would use a mini-submarine, along with Red Cross scuba divers with underwater cameras, to search the waters around Utoya.

An undetermined number of campers jumped into the sea in an attempt to flee from the gunman, who in turn opened fire on them. Police said at least four or five people were still missing.

By late Saturday, the death toll from the island rampage stood at 85, bringing the overall number of dead, including the Oslo bombing, to 92.

Police indicated it could go as high as 98 if all those missing are found dead, FOX News reported.

In Oslo, where flags flew at half-staff and members of the public and Norwegian royal family left flowers and candles at a makeshift memorial, Sponheim urged residents to stay away from buildings damaged by the car bomb and noted there were still some body remains in the buildings.

Norwegian and international media, meanwhile, tried to dissect the psyche of the boyish-looking, blond-haired Breivik. The (London) Times described him as an affluent and educated loner who lived with his mother in a wealthy area of western Oslo and had no criminal record apart from a traffic conviction ten years ago.

The Times said he set up Facebook and Twitter accounts July 17, listing Franz Kafka's "The Trial" and George Orwell's "Nineteen Eighty-Four" among his favorite books and calling the television series "Dexter," about a serial killer, his favorite show.

His business was described as buying, selling and managing stocks, project developing and real estate, The Times said. He also recently established an organic farming company and bought 6.6 tons of fertilizer -- a potential bomb component.

The Associated Press and NewsCore contributed to this report.