In England, a 26-year-old advertising agency employee caters to multinational clients but on the side has been communicating with a secretive band of strangers devoted to supporting WikiLeaks.

Halfway around the world, a 24-year-old in Montana has used a publicly available - and, according to security experts, suddenly popular - software program called Low Orbit Ion Cannon with the goal of shutting down Web sites of WikiLeaks' perceived enemies.

Since releasing a vast cache of diplomatic cables this month, the anti-secrecy group WikiLeaks has been the focus of intense criticism: for divulging classified materials, embarrassing the U.S. government and potentially endangering lives. But it has also engendered the frenzied support of an expanding and loosely defined global collective that seems intent on speaking out - and in some cases waging war on WikiLeaks' behalf.

The most prominent of those groups is known as Anonymous, which this past week sought to disable the Web sites of several U.S. companies as part of what it called Operation Payback.WikiLeaks has also drawn the support of traditional civil rights organizations and advocacy groups, which see the controversy surrounding WikiLeaks as an important test of U.S. commitment to freedom of the Internet.

Several groups have expressed dismay over recent statements by U.S. politicians suggesting that WikiLeaks founder Julian Assange should be branded an international terrorist or perhaps even assassinated. In a series of ads to be published in U.S. newspapers this week, the Australian activist group GetUp calls on Washington to "stand up for our shared democratic principles of the presumption of innocence and freedom of information."

But it is the activities of Anonymous and its members that have caused the greatest stir online. In addition to launching "denial of service" attacks on various Web sites, the group's members have issued open letters in support of WikiLeaks and sought to drum up support for Assange as Time magazine's "Person of the Year." (By Sunday, he was in the No. 1 spot in Time's poll, with nearly 400,000 votes.)

When contacted through Twitter, Anonymous members said in recent days they have been driven by fears of civil rights intrusions and totalitarian futures.

"Whether the fear is logical or not, I see a lot of aspects of George Orwell and Aldous Huxley's dystopias coming into play in a lot of the U.S. government's policies," said the Montana man, who said he was a staffer at a group home for mentally disabled adults.

The man, who declined to be named because he said he feared arrest, compared the attacks on U.S. companies' Web sites - known to some as "hacktivism" - to earlier versions of civil protests: "It was like the sit-ins during the 1960s when you had college students taking up space in restaurants."

Now, Anonymous is helping a wider audience comb through the WikiLeaks documents in a new campaign called Operation Leakspin. On the social media Web site Reddit, the Montana member of Anonymous said he helps moderate a "sub-Reddit" section where users sift through various leaked State Department cables. Reddit users post comments, vote on which cables are the most revelatory and click back to WikiLeaks' site to view the entire cable.

The Montana man said Reddit allows the Anonymous movement, whose members chat with one another on hard-to-find servers and in instant message rooms, to influence a broader readership.

"Rather than putting these cables on our own server, we're making it more available to everyone. We got everyone's attention with the distributed denial of service attacks, so now we're looking more at what's in the leaks," he said. "The call now is to stop the attacks. I didn't do much of those. I wasn't one of the people who thought it was necessary, but what I think doesn't matter. The majority has to think it."

It's unclear how many people consider themselves as part of the Anonymous movement. Various Twitter groups seemingly affiliated with the organization provide rough estimates of its influence: Anonops has nearly 10,000 followers; Operation Leakspin has more than 1,300 followers; Anonymous Operations has about 1,200 followers.

The group achieved some infamy two years ago when WikiLeaks published the private emails of former vice presidential candidate Sarah Palin and said it received the files from Anonymous.

Anonymous members meet on other Web sites, whose addresses are publicized on Twitter or elsewhere. They issue announcements on www.anonops.blogspot.com , featuring information about the locations and times of upcoming demonstrations supporting Assange in London or at a local courthouse.

"PROTEST!" reads one headline on the Web site, announcing a demonstration on Tuesday outside the Westminster Magistrates' Court in London. "Julian Assange will be appearing at court for a bail hearing please come and make your voice heard!"

On anonymousfreedom.org , members urge people to go on Reddit and focus on particular countries: "We are, at the moment, particularly interested in china and iran!" the site says, directing people to cables between the State Department and overseas embassies regarding sales of Chinese sales of weapons to Iran; or to Kenya against Somalia.

In England, the 26-year-old ad agency employee said he communicates with fellow Anonymous members on hard-to-find Internet Relay Chat rooms where hundreds of users can talk to one another without disclosing their identities. The movement, he said, is inspired by many literary sources, including science fiction writer Isaac Asimov and his "Foundations" series about the future.

"The whole Asimov series is about the lack of transparency, but after time, everything becomes clear," he said. "A lot of the people in Anonymous have grown up with the Internet and see a future where the Internet is cut back, where we have no net neutrality, and there are different tiers of service and it isn't free to all.''

The English member of Anonymous guided a Post reporter to a chat room of fellow members who had nicknames like "steerpike," "pheadanon" and "Grommell."

There, on a collaborative site called Piratepad.net, Anonymous members tapped out their reasons for defending WikiLeaks. "We've seen the power the Internet can have in organizing the masses," one member said. "Look at the protests in Iran. I fight for wikileaks because I don't want to live in a future where people cannot talk about dissent without attracting the notice of government bouncers in black suits."

Another person revealed a more ulterior motive in the Piratepad chat room: "The most important result from doing these attacks is the media exposure," the Anonymous member wrote. "It does provide somewhat of a rush, and it is very empowering to note how many people are passionate about their freedom. We are here for exposure, period, NOT damage."

shapirai@washpost.com warrickj@washpost.com