CNN has not independently confirmed Breivik is the author of the document, which says it is designed to be circulated among sympathizers and bears his name.

Judge Kim Heger ordered him held in custody for eight weeks until his next court appearance, Norway state broadcaster NRK reported.

Police said Breivik confessed to the attacks, while his lawyer said the suspect wanted to "explain himself" in court, NRK reported before the court appearance.

Authorities in Norway now believe that there were fewer victims in Friday's mass shooting than previously thought, they told CNN Monday.

Police spokesman Henning Holtaas would not say by how many the death toll would be reduced, saying only that details and the numbers of dead would be released at a news conference later in the day. 

"It is important for Norwegian police to be 100% sure before releasing the names of the dead," he told CNN.

Authorities had been saying at least 93 people were killed and 96 wounded in the terror attacks.

The Norwegian government called for a national moment of silence in their memory Monday, ordering trains halted as part of a nationwide observance to remember the victims of Friday's bombing in downtown Oslo and shooting at a political youth retreat on Utoya island.

Court officials were among many who stood in silence to mark the moment at noon.

The suspect was denied a public stage at his hearing, because Judge Heger closed the court appearance to the public and the media.  

Police asked the court to keep the media out because investigators have not ruled out that others were involved and were concerned the suspect could try to send messages to others, Holtaas told CNN by telephone Monday.

Heger cited "security reasons and because of a concern that it would impede the investigation," court communications director Irene Ramm told CNN.

More than 70,000 people had joined a Facebook page titled "Shut the courtroom doors on Monday," urging the court to close the hearing.

Attorney Geir Lippestad, who said he represented Breivik, told Norwegian TV2 that the suspect feels the terrorist attacks were "horrible," but "in his head (they) were necessary."

During the TV2 interview late Saturday, Lippestad said his client "is ready to explain himself" at Monday's court hearing, which is similar to an arraignment.

CNN's attempts to reach Lippestad have been unsuccessful.

The suspect has been charged with two acts of terror, one for the bombing and one for the mass shooting, Holtaas said.

In Norway, the maximum sentence on such a charge is 21 years. However, if the court deems that a person could be a future threat, then they can be sentenced to "preventative detention," Holtaas said. Under that type of sentence, a person would serve the maximum sentence of 21 years and then the court could assess an extension if the person was still deemed a threat, he said. 

Breivik, a Norwegian, has told investigators he acted alone and was not aided in the planning, acting National Police Chief Sveinung Sponheim told reporters Sunday. But authorities have not ruled out that others may have been involved or helped him along the way, he said.

Sponheim said there has been "no progress" in ascertaining what the suspect's motive might have been. But he said that investigators were studying a manifesto that authorities believe was published online the day of the attack.

The suspect told investigators during interviews that he belonged to an international order, The Knights Templar, according to Norwegian newspaper VG, which cited unnamed sources.

He described the organization as an armed Christian order, fighting to rid the West of Islamic suppression, the newspaper said. He also told investigators he had been in contact with like-minded individuals and said he counts himself as a representative of this order, it said.

Holtaas declined to confirm the news report, saying "we are not commenting on such details."

The newspaper report mirrors statements in the manifesto.

Breivik requested permission to appear in court in a uniform, Lippestad told Norwegian newspaper Aftenposten and NRK, Norwegian state TV.

Lippestad told the news agencies he did not know what kind of uniform Breivik wanted to wear.

In the manifesto, there are photographs of Breivik wearing what appears to be a military uniform that features an altered U.S. Marine Corps dress jacket with Knights Templar medals.

Historically, the Knights Templar were Christian Crusaders who helped fight against Muslim rule of the Holy Land in the Middle Ages.

The manifesto rants against Muslims and their growing presence in Europe and calls for a European civil war to overthrow governments, end multiculturalism and execute "cultural Marxists."

The author of the document identifies himself as Breivik and indicates he is from Norway. CNN could not independently verify that Breivik wrote the document, and Norwegian authorities would not confirm that the man in their custody wrote the manifesto, saying it was part of their investigation.

Authorities allege that Breivik killed seven people Friday by setting off a car bomb in downtown Oslo that targeted government buildings, then traveled 20 miles to Utoya island and killed about 86 teens and young adults in an ambush at a political youth retreat.

The suspect was carrying a considerable amount of ammunition when he surrendered to authorities, Sponheim told reporters.

Investigators will conduct autopsies over the next few days, Sponheim said, and the identities of the victims will be released once all the next-of-kin have been notified.

Among those killed on the island was Trond Berntsen, the step-brother of Crown Princess Mette-Marit, according to a statement released by the Royal House Communications office.

At least four people have not been accounted for around Utoya island, with investigators searching the waters nearby for victims who may have drowned trying to escape the shooter.

On Sunday, police raided a property the suspect owned in the eastern Oslo area of Slettelokka looking for explosives.

"We were there with dogs but found nothing of any value as evidence," Sponheim said.

Police said Sunday that the area around the blast site would remain cordoned off, but members of the public in the area were not at risk.

CNN's Jonathan Wald, Michael Holmes, Jennifer Deaton, Erin McLaughlin, Chelsea J. Carter and Greg Botelho contributed to this report.