LONDON » When the English Defense League sprang to life two years ago, it had fewer than 50 members — a rough-and-tumble bunch of mostly white guys shouting from a street corner about what they viewed as uncontrolled Muslim immigration.

Now, the far-right group mentioned by confessed Norway gunman Anders Behring Breivik as an inspiration says its ranks have swollen to more than 10,000 people, a spectacular rise its leaders attribute to the immense global power of Facebook and other social networking sites.

"I knew that social networking sites were the way to go," EDL leader Stephen Lennon told The Associated Press. "But to say that we inspired this lunatic to do what he did is wrong. We’ve never once told our supporters its alright to go out and be violent."

A Facebook page under Breivik’s name was taken down shortly after the attacks last week. A Twitter account under his name had only one Tweet, on July 17, loosely citing English philosopher John Stuart Mill: "One person with a belief is equal to the force of 100,000 who have only interests."

Norwegian investigators have pored through data on Breivik’s computer and say they now believe he was acting alone. They have also said they haven’t found any links of concern between Breivik and far right British groups such as the EDL.

In addition to Facebook, Myspace, and Twitter, the Internet hosts thousands of forums for far-left, far-right and other extremist groups. In Germany alone, far-right groups ran some 1,000 websites and 38 online radio stations as of late last year with many aimed at recruiting followers. Social networking sites, complete with politically charged music, are particularly drawing younger audiences who increasingly get their information outside of traditional media.

Extremists "still favor online chat platforms — often with several hundred participants — but they are increasingly turning to social media," said Germany’s Office for the Protection of the Constitution, which called the danger of recruitment "considerable."

Intelligence and law enforcement officials have mixed feelings about the sites. On one hand, they recognize the potential for recruiting groups or individuals into violent movements. On the other, the sites allow officials to track and catch perpetrators. Germany’s interior minister, Hans-Peter Friedrich, told local media this week that he’s more worried about extremists who go underground and "radicalize in secret."

Most agree that the most violent criminals often give little to no clear warning of the deadly acts they are about to commit, and that sometimes it’s difficult to know when a person is simply boasting or whether their online activity suggests they could become killers.

What’s undeniable is the social media’s power to bring together people with like-minded views.

"Fifty years ago, if you believed that the Earth was populated by spies from Jupiter, it would have taken you quite some time to find someone else who shared the same belief," said Bob Ayers, a London-based former U.S. intelligence official. "That’s not the case today. Social networking sites have changed the mathematics of things, and with that change, comes both pros and cons."

Several of the email addresses to which Breivik sent his 1,516-page manifesto hours before the Oslo bombing matched Facebook profiles of people flaunting neo-Nazi or ultra-nationalist symbols.

Those profiles, in turn, were set up to connect with like-minded people. One apparently Italian addressee — whose profile picture shows a swastika, the SS-symbol, and a skull — linked to Facebook groups representing "Fascist Music," the biography of former Italian fascist dictator Benito Mussolini, as well as firearms.

His list of 462 "friends" showed several people with similar profiles, including some with the symbols or illustrations of the Knights Templar, a group that Breivik said he joined after meeting with a group of right-wing men in London.

Another addressee, showing off his pumped up torso and shaved head, lists the anti-immigration British National Party as his political views.

The British National Party, which won its first seat in European parliamentary elections last year, recently encouraged its members to use social media outlets. It even suggested that supporters use hashtags such as (hash)nationalist and (hash)BNP — techniques designed to capture a larger audience on a specific topic.

"Social networking is an important way of keeping in touch with the British National Party, and taking small, easy actions to promote our fight for our identity and culture," the BNP said on its site. "It’s just one way you can make a difference and show you care about the cause we all believe in."

The group recommended its supporters post pro-nationalist quotes on Facebook to inspire friends to take action.

Some analysts say that although it’s clear social media plays an important role in strengthening the far-right’s sense of identity and solidarity, it’s too early to say how much Facebook and Twitter have helped contribute to extremist violence.

"The fact that we have more blogs, more online forums, doesn’t mean we have a greater risk of terrorism," said Matthew Goodwin, a politics lecturer who recently published a book on the far right in Britain. "Even if they hold radical, extreme views, it doesn’t mean they’re pro-violence."

Facebook says it relies on its community to police the site and usually only steps in when individuals or groups are inciting violence or hate. It would not comment on whether it was cooperating with law enforcement agencies looking into the Norway massacre.

"Facebook has a team of professionals that removes content that violates our policies, which includes content that’s hateful, makes actionable threats, or includes nudity and/or pornography," said Facebook spokesman Andrew Noyes.

Daniel Hodges, a spokesman for Searchlight, a UK magazine that campaigns against far-right extremism, said the Internet has allowed "all sorts of appalling viewpoints" to be read by anyone. "How many people over the world today have now read Breivik’s manifesto?" he said.

The Internet often lets groups like the EDL come across as more powerful than they really are, he said.

"(The Internet) allows them to reach their membership relatively speedily, relatively anonymously. It enables them to give a perception of a significant critical mass. But many far right activists live online, not in the real world," Hodges said.

During a recent British election, the BNP suffered from a lack of grassroots support on the ground, even though its website received massive online traffic.

The definition of what counts as hate speech also varies from one country to another, and in the U.S. much of it is protected under the First Amendment. Denying the Holocaust, for example, is illegal in many European countries but not in the U.S.

U.S. laws also protect Internet companies from being held responsible for the content on their sites.

Rather than automatically take down pages that are in the gray area, some civil libertarians think it’s better for social media sites to "err on the side of caution" and let the community handle it.

"Facebook and social media in general tend to be very self-correcting," said Jillian York, director of International Freedom of Expression at the Electronic Frontier Foundation, a civil-liberties group in San Francisco.

"A lot of times you see people who oppose the hate speech taking over the (hate) groups. That tends to be more effective than taking the page down."

The Czech Republic’s counterintelligence service called the Internet the "No. 1" propaganda tool for extremists in their terrorism report last year.

"There is a significant increase in activities of far right extremists in social networking sites, especially on Facebook. In connection with that, a relatively new phenomenon has appeared of groups which are joined, besides the extremists, also by common citizens … As a result, the extremist views are becoming popular and spread among the public."

Germany viewed the threat in a similar way.

"The use of the Internet has become a fixture for German right-wing extremists in spreading their ideology, preparing their activities, campaigns and other events as well as the communication with their followers and sympathizers," Germany’s domestic intelligence agency said in its latest report published earlier this month.

Lennon, meanwhile, may find himself spending even more time in the virtual far-right world. The 28-year-old newlywed with a handful of missing teeth is banned from going anywhere near protests. He also claims to have had his assets frozen pending a police investigation.

Despite the setbacks, Lennon said his group is growing — and even moving beyond the need for social media.

"We’ll keep talking to people about what the EDL stands for, but we don’t actually need places like Facebook anymore. We’ve already built our network and it’s growing."

Also contributing to this report were Barbara Ortutay in New York, in Gabriele Steinhauser in Brussels, Karel Janicek in Prague, Juergen Baetz in Berlin and Sylvia Hui in London.