The police said they were questioning a right-wing Christian on Saturday over the twin attacks on a youth camp and the government headquarters that killed 92 people in Norway's deadliest post-war tragedy.
As harrowing testimony emerged from the holiday island where scores of youngsters were mown down by a gunman posing as a policeman, Norway's premier said the country would emerge stronger from the 'cruel act of violence'.
'Never since the Second World War has our country been hit by a crime on this scale,' Jens Stoltenberg told journalists as the police searched for more bodies on the idyllic Utoeya island.
Their latest death toll from the island massacre
stood at 85 while seven people died in the Oslo bombing.
While there was no official confirmation of the suspect's identity, he was widely named by the local media as Anders Behring Breivik.
According to information the suspect posted online, he is an 'ethnic' Norwegian and a 'Christian fundamentalist,' police spokesman Roger Andersen said, adding his political opinions leaned 'to the right'.
The police commissioner Sveinung Sponheim confirmed that the suspect was a 32-year-old Norwegian who had posted anti-Muslim rhetoric online.
Norwegian media reported that the blond-haired Behring Breivik described himself on his Facebook page as 'conservative', 'Christian', and interested in hunting and computer games like World of Warcraft and Modern Warfare 2.
On his Twitter account, he posted only one message, dated July 17, in English based on a quote from British philosopher John Stuart Mill: 'One person with a belief is equal to a force of 100,000 who have only interests.'
The attacks on Friday afternoon were western Europe's deadliest since the 2004 Madrid bombings.
While there had been initial fears they might have been an act of revenge over Norway's participation in the campaigns in Afghanistan and Libya, the focus shifted when it emerged the suspect was a native Norwegian.
The police lifted an advisory telling residents to stay home.
But in a sign of the population's nervousness, the police arrested one young man armed with a knife at a hotel outside Oslo where some of the survivors had gathered and Stoltenberg had just arrived for a visit.
Seven of the victims were killed in a massive explosion which ripped through government buildings, including Stoltenberg's office and the finance ministry, in downtown Oslo.
It is thought that the bomber then caught a ferry to nearby Utoeya wearing a police sweater.
On arrival, he claimed to be investigating the bomb attack and began opening fire with an automatic weapon after beckoning youngsters towards him.
Witnesses described scenes of panic and horror among the 560 people attending the youth camp. Some who tried to swim to safety were even shot in the water.
Among the wounded was Adrian Pracon, who was shot in the left shoulder.
Speaking to Australia's ABC network from hospital, he said the scene on the island was like a 'Nazi movie'.
'He was shooting people at close range and starting to shoot at us. He stood first 10 metres from me and shooting at people in the water,' he said.
'When I saw him from the side yelling that he was about to kill us, he looked like he was taken from a Nazi movie or something.
'He tried everyone, he kicked them to see if they were alive, or he just shot them.
Stine Haheim, a Labour party lawmaker who was on the island at the time of the shooting, said that the gunman had carried out his killings methodically.
'He was very calm. He was not running, he was moving slowly and shooting at every person he saw,' she said. 'We just jumped in the water and started swimming.'
The Norwegian police said they feared there could also be explosives on the island. According to a spokeswoman for a farm inputs cooperative, the suspect bought six tonnes of fertiliser — which can be used to make bombs — in May.
'We sold him six tonnes of fertiliser, which is a relatively standard order,' Oddny Estenstad said.
Stoltenberg had been due to give a speech on Saturday to the 560 people attending the youth camp on the island, organised by the ruling Labour party.
As he visited some of the survivors, the prime minister spoke of his own anguish at the massacre on an island to which he was a frequent visitor.
'Many of those who have died were friends. I know their parents and it happened at a place where I spent a long time as a young person... It was a paradise of my youth that has now been turned into hell,' he said.
Stoltenberg said he had been deeply moved by speaking to youngsters who had told him they swam to shore, in some cases helping friends who had been shot.
He said Norway must ensure that the attacks does not undermine the fundamental values of its society.
'We are an open society, a democratic society, we are a society where we have a very close relationship between politicians and the people.'
There was widespread international condemnation with the US president, Barack Obama, saying the attacks were 'a reminder that the entire international community has a stake in preventing this kind of terror from occurring.'
Britain's Queen Elizabeth II also wrote to King Harald V of Norway to offer sympathy over 'the dreadful atrocity'.
The Norwegian capital is a well-known symbol of international peace efforts and home to the Nobel Peace Prize.
Soruce : New Age