Oslo, Norway ? He wanted to ignite “a revolution,” one that would upend contemporary Norwegian and European society. The goal: to purge the continent of Muslims and punish the “indigenous Europeans” who had failed to protect their nations from “cultural suicide.”

As Norway grieved for the 93 people cut down in twin terrorist attacks, the radical views of the accused killer came into clearer view Sunday, and raised questions about the threat posed by far-right extremists in this country and the extent to which the authorities can control it.

The threat reflects a bitter resentment toward demographic changes that reach beyond Norway to neighbors such as Sweden, Denmark, Finland and the Netherlands, where far-right and anti-immigrant parties have made major political gains in recent years.

Investigators here in the Norwegian capital continued to pore over a 1,500-page treatise that was apparently posted on the Internet by suspect Anders Behring Breivik shortly before a massive bomb exploded Friday in downtown Oslo, followed by a shooting spree at a youth camp tied to the ruling Labor Party, which is relatively more tolerant toward immigration.

The chilling manifesto advocates an armed campaign against the Muslims it says are overrunning Europe. A hate-filled brew of political, ideological and militaristic cant, the treatise denounces Europeans who support multiculturalism and argues for spectacular violence using tactics similar to those seen Friday, such as adopting a police disguise to fool victims before killing them.

Breivik has admitted to the twin attacks, which left nearly 100 injured and at least four people still missing, without accepting criminal responsibility for them, police said.

His lawyer, Geir Lippestad, told Norwegian public broadcaster NRK on Sunday that Breivik “wanted a change in society and, from his perspective, he needed to force through a revolution. He wished to attack society and the structure of society.”

The 32-year-old is expected to appear at a court hearing today and wants to “explain himself,” Lippestad added.

Authorities are now trying to determine the credibility of a claim in the manifesto that, in London nine years ago, Breivik attended a meeting of like-minded radicals calling themselves the Knights Templar.

Trouble long brewing

Even before Friday’s attacks, right-wing fanatics had long been part of Norway’s social and political landscape.

They were especially active throughout the 1980s and ’90s, in the form of skinhead gangs engaged in street violence. For many years, far-right groups were considered the main source of concern in the Norwegian intelligence agency’s threat assessment.

But their influence was muted after a young biracial man was knifed to death in 2001 by a right-wing extremist, a killing that shocked a country that prided itself on peaceful coexistence.

“That caused such a popular uproar against these movements that it stopped recruitment to a certain extent,” said Tore Bjorgo, a professor at the Norwegian Police University College and an expert on violent subgroups.

A crackdown by police and preventive work by social organizations succeeded in breaking up many of the groups in the last decade, enough that they were no longer seen as much of a threat.

At the same time, immigration by Muslims — who still represent only a few percentage points of Norway’s population — and the Sept. 11 attacks turned authorities’ attention to radical Islam and stirred up a new set of fears.

Polls show that as many as half of Norwegians oppose the government’s immigration policy, which they deem too liberal. Breivik’s own anti-Islam obsession comes against a backdrop of a general hardening of sentiment toward immigrants, reflected in the rise of Norway’s right-wing populist Progress Party, which won more than 20 percent of the vote in an election two years ago.

Such right-wing political muscle is also evident in Denmark and the Netherlands, where strong electoral gains by such parties have forced the governments to accede to some of their demands in order to pass other legislation.

“The debate about Muslims in Norway has changed in the last decade,” said Thomas Hylland Eriksen, a professor at the University of Oslo. “The threshold has been lowered about what you can say” about Islam and its adherents, with statements that would have been regarded as inflammatory a decade ago now an acceptable part of social discourse.

Breivik joined the Progress Party, but reportedly dropped out several years ago because he found its anti-immigrant stance too weak. He began nursing far more extreme views, some of which he appears to have expressed in Internet postings.

Those views don’t reserve their anger just for Muslims themselves. The ire of extremists like Breivik extends to “what they perceive as the political elite and what they perceive as the socialist establishment’s betrayal of the Norwegian nation,” Eriksen said.

“I often ask myself, who do they hate the most — Muslims or people who defend Muslims? It seems to me they hate us the most, the people they see as the politically correct establishment,” he said.

Loose organization

Right-wing radicals like Breivik are now presenting authorities with a different kind of challenge from that posed by the skinhead groups of the ’80s and ’90s, experts say. They do not belong to organized groups but rather form loose networks, often in online communities, which are harder to track and infiltrate.

“They are not street-oriented,” Bjorgo said. “They are more intellectual; their main arena is discussion forums and Internet debates. … It’s a much more sophisticated kind of right-wing activism.”

This has limited the authorities’ room for maneuver and may have caused them to underestimate the danger posed by such extremism, analysts say.

In its most recent threat assessment, Norway’s intelligence service said that right-wing extremists have been only “slightly active” in recent years, but “an increased level of activity in 2010 is expected to continue in 2011.”

Breivik does not appear to have been on anyone’s radar before Friday’s terrible events.

“His statements were fiercely anti-Islam, but they were not pro-violence. He always argued in a political way, using political means, which is very typical for that movement,” Bjorgo said. “That is one of the reasons why he was never detected by the security service, because there was nothing apparently special about him.”