Amid an outpouring of grief and solidarity, police in Norway are widening their investigation following a claim by the sole suspect in Friday's killings that he had worked with collaborators.
People gathered in the capital, Oslo, on Tuesday to pay homage to the victims of the twin attacks that left 76 people dead.
Anders Behring Breivik, a 32-year-old Norwegian man, is accused of carrying out the bombing in Oslo and the shooting spree on the resort island of Utoeya.
"The whole street is completely filled with flowers and candles." Al Jazeera's Harry Smith reported from Oslo.
Up to 150,000 people paid homage in Oslo on Monday evening: mourners sang songs and cheered in solidarity while others placed flowers on a memorial wall next to the city hall.
Jens Stoltenberg, the prime minister, told the crowds in Oslo that Norway would not be defeated by the tragedy.
"Evil can kill a person, but it can never defeat a whole nation," he said, to loud applause.
"With the strongest of all the world's weapons - freedom of speech and democracy - do we set the course for Norway post 22 July 2011," Stoltenberg said.
The original aim had been to hold a memorial procession for those who lost their lives in the bombing and shooting, but the numbers of people were so great that the crowds simply held a mass gathering.
'Two further cells'
Earlier, at Monday's court hearing in Oslo, Breivik said on being remanded in custody that he had "two further cells" in his organisation.
A senior court official declined to elaborate on Breivik's claim after the hearing. Instead, Geir Engebretsen, the court's chief, repeated the ruling of Judge Kim Heger who is trying Breivik's case.
Earlier Heger said: "The accused has made statements today that require further investigation, including that 'there are two more cells in our organisation'."
Breivik had previously said he acted alone in the attacks. Breivik also calmly said in court that that he expects to spend the rest of his life in prison, officials said.
The judge ordered eight weeks' detention for Breivik, who has admitted to the attacks. Breivik told the court that he acted to save Europe from Islam.
Heger said that Breivik would be locked up alone with no incoming letters, media nor visitors except for his lawyer. A trial could be a year away.
'Perception of reality'
Breivik had requested his hearing be open to the public in order to "explain fully what he's done, and more importantly, why he did it", Al Jazeera's Harry Smith reported from Oslo.
Geir Lippestad, Breivik's lawyer, told NRK television his client had expected to be shot dead by angry Norwegians on his way to court.
But after requests from prosecutors and police to close the arraignment, the judge barred the media and public from attending.
"He has a completely different perception of reality than us other Norwegians, for instance he thinks that torture exists in prisons in Norway," Lippestad said.
In front of a proceeding in Oslo, Lippestad said that his client says "he is sorry that he had to do this, but it was necessary to start a was in Europe and a revolution in the western world".
Breivik was arrested under the country's terrorism laws but will not learn the actual charges against him until the investigation is concluded, closer to his trial date.
"I have never come across a lawyer who has gone before a proceeding to say he is not sure whether his client is insane.
"This is the lawyer that is going to defend him. Must question whether this court will actually go to trial," Harry Smith said.
In an interview with Norway's TV2, Breivik's father, Jens Breivik, said he last saw his son 17 years ago and was horrified by what he had done.
"In my darkest moments, I think that rather than killing all those people, he should have taken his own life," Jens Breivik said.
"I feel shame and grief for what has happened. I really wish it was undone."
Revised death toll
Norwegian police earlier revised the death toll from the bomb and shooting attack to 76 people from a previous estimate of 93, citing difficulties in gathering information at Utoeya, where the shooting spree occurred.
At least eight people were killed in the bomb blast outside government buildings in central Oslo, and a further 68 were killed during the shooting in Utoeya, 40km away, where a Labour party youth camp was being held.
The attacks wounded at least 100 other people.
Nick Spicer reports on the court proceedings in Oslo
The Norwegian royal family said that the stepbrother of the crown princess was one of those killed on Utoeya.
Trond Berntsen was a 51-year-old retired policeman who was serving as a volunteer guard on the island, the Verdens Gang newspaper reported.
Handling of attacks
Police continued to hunt for possible accomplices and defended the hour it took before they responded to the Utoya attack.
There has been an official response to questioning of the police's handling of the attacks.
"The police have said that they have reviewed and they will continue to review their operation, but they have said that it was the quickest response they could make.
"They cite the lack of a helicopter to take them there [to Utoya]" Harry Smith said.
The murderous "crusade" was designed to end a centuries-long Muslim colonisation of Europe, Breivik said in a 1,500-page manifesto released on the internet.
Police have declined to comment on Breivik's motives, but Geir Lippestad, his lawyer, has said Breivik told him he wanted to send a "warning" to the Labour party.
'Cruel' but 'necessary'
The Utoeya shooting spree lasted for about 90 minutes before police arrested Breivik.
Breivik did not resist his arrest, though he had ammunition remaining, police said.
During weekend interrogation, Breivik told police that his attacks were "cruel" but "necessary".
Interview with Jens Stoltenberg, the prime minister of Norway
While he "admitted responsibility" according to police, Lippestad said he was not accepting "criminal responsibility", and that his client felt he had done "nothing reprehensible".
The attacks have caused outrage in Norway, and some have called for the reinstatement of the death penalty, which was eliminated decades ago.
The maximum prison sentence facing Breivik is 21 years' imprisonment, though legal experts said the sentence could be extended indefinitely for five years at a time.
Police have not ruled out the involvement of a second assailant, and on Sunday they detained several people in a swoop on two Oslo properties thought to be connected to the attacks.
The suspects were released shortly afterwards, and no explosives were found.
The Friday afternoon attacks were western Europe's deadliest since the 2004 Madrid bombings, which were carried out by al-Qaeda, and the worst in Norway since the second world war.
Investigators have been poring over the manifesto in which Breivik said he had been preparing the "martyrdom operation" since at least late 2009.
Part diary, part bomb-making manual and part Islamophobic rant, the "compendium" details how he set up fake mining and farming businesses to prepare the attacks.
Anti-fascist monitors have said Breivik was a member of a Swedish neo-Nazi internet forum, Nordisk.