Not limiting their activities to the earthly realm, U.S. and British spies have infiltrated the fantasy worlds of World of Warcraft and Second Life, conducting surveillance and scooping up data in the online games played by millions of people across the globe, according to newly disclosed classified documents.

Fearing that terrorist or criminal networks could use the games to communicate secretly, move money or plot attacks, the documents show, intelligence operatives have entered terrain populated by digital avatars that include elves, gnomes and supermodels.

The spies have created make-believe characters to snoop and to try to recruit informers, while also collecting data and contents of communications between players, according to the documents, disclosed by the former National Security Agency contractor Edward Snowden. Because militants often rely on features common to video games - fake identities, voice and text chats, a way to conduct financial transactions - U.S. and British intelligence agencies worried that they might be operating there, according to the papers.

Online games might seem innocuous, a top-secret 2008 National Security Agency document warned, but they had the potential to be a “target-rich communication network” allowing intelligence suspects “a way to hide in plain sight.” Virtual games “are an opportunity!” another 2008 National Security Agency document declared.

But for all their enthusiasm - so many CIA, FBI and Pentagon spies were hunting around in Second Life, the document noted, that a “deconfliction” group was needed to avoid collisions - the intelligence agencies may have inflated the threat.

The documents do not cite any counterterrorism successes from the effort, and former U.S. intelligence officials, current and former gaming company employees and outside experts said in interviews that they knew of little evidence that terrorist groups viewed the games as havens to communicate and plot operations.

Games “are built and operated by companies looking to make money, so the players’ identity and activity is tracked,” said Peter W. Singer of the Brookings Institution, an author of Cybersecurity and Cyberwar: What Everyone Needs to Know. “For terror groups looking to keep their communications secret, there are far more effective and easier ways to do so than putting on a troll avatar.”

The surveillance, which also included Microsoft’s Xbox Live, could raise privacy concerns. It is not clear exactly how the agencies got access to gamers’ data or communications, how many players may have been monitored or whether Americans’ communications or activities were captured.

One U.S. company, the maker of World of Warcraft, said that neither the National Security Agency nor its British counterpart, the Government Communications Headquarters, had gotten permission to gather intelligence in its game. Many players are Americans, who can be targeted for surveillance only with approval from the nation’s secret intelligence court. The spy agencies, though, face far fewer restrictions on collecting certain data or communications overseas.

“We are unaware of any surveillance taking place,” said a spokesman for Blizzard Entertainment, based in Irvine, Calif., which makes World of Warcraft. “If it was, it would have been done without our knowledge or permission.”

A spokesman for Microsoft declined to comment. Philip Rosedale, the founder of Second Life and a former chief executive officer of Linden Lab, the game’s maker, declined to comment on the spying revelations. Current Linden executives did not respond to requests for comment.

A Government Communications Headquarters spokesman would neither confirm nor deny any involvement by that agency in gaming surveillance, but said its work is conducted under “a strict legal and policy framework” with rigorous oversight. A National Security Agency spokesman declined to comment.

Intelligence and law enforcement officials became interested in games after some became enormously popular, drawing tens of millions of people worldwide, from preteens to retirees. The games rely on lifelike graphics, virtual currencies and the ability to speak to other players in real time. Some gamers merge the virtual and real worlds by spending long hours playing and making close online friends.

In World of Warcraft, players share the same fantasy universe - walking around and killing computer-controlled monsters or the avatars of other players, including elves, animals or creatures known as orcs. In Second Life, players create customized human avatars who can resemble themselves or take on other personas - supermodels and bodybuilders are popular - who can socialize, buy and sell virtual goods, and go places like beaches, cities, art galleries and strip clubs. In Microsoft’s Xbox Live service, subscribers connect online in games that can involve activities like playing soccer or shooting at each other in space.

According to U.S. officials and documents that Snowden provided to The Guardian, which shared them with The New York Times and ProPublica, spy agencies grew worried that terrorist groups might take to the virtual worlds to establish safe communications channels.

In 2007, as the National Security Agency and other intelligence agencies were beginning to explore virtual games, National Security Agency officials met with the chief technology officer for the manufacturer of Second Life, the San Francisco-based Linden Lab. The executive, Cory Ondrejka, was a former Navy officer who had worked at the National Security Agency with a top-secret security clearance.

He visited the agency’s headquarters at Fort Meade, Md., in May 2007 to speak to staff members over a brown bag lunch, according to an internal agency announcement. “Second Life has proven that virtual worlds of social networking are a reality: come hear Cory tell you why!” said the announcement. It added that virtual worlds gave the government the opportunity “to understand the motivation, context and consequent behaviors of non-Americans through observation, without leaving U.S. soil.”

Ondrejka, now the director of mobile engineering at Facebook, said through a representative that the National Security Agency presentation was similar to others he gave in that period, and declined to comment further.

Even with spies already monitoring games, the National Security Agency thought it needed to step up the effort.

“The Sigint Enterprise needs to begin taking action now to plan for collection, processing, presentation and analysis of these communications,” said one April 2008 National Security Agency document, referring to “signals intelligence.” The document added, “With a few exceptions, NSA can’t even recognize the traffic,” meaning that the agency could not distinguish gaming data from other Internet traffic.

By the end of 2008, according to one document, the British spy agency, known as GCHQ , had set up its “first operational deployment into Second Life” and had helped the police in London in cracking down on a crime ring that had moved into virtual worlds to sell stolen credit card information. The British spies running the effort, which was code-named Operation Galician, were aided by an informer using a digital avatar “who helpfully volunteered information on the target group’s latest activities.”

Though the games might appear to be unregulated digital bazaars, the companies running them reserve the right to police the communications of players and store the chat dialogues in servers that can be searched later. The transactions conducted with the virtual money common in the games, used in World of Warcraft to buy weapons and potions to slay monsters, are also monitored by the companies to prevent illicit financial dealings.

In the 2008 National Security Agency document, titled “Exploiting Terrorist Use of Games & Virtual Environments,” the agency said that “terrorist target selectors” - which could be a computer’s Internet Protocol address or an email account - “have been found associated with Xbox Live, Second Life, World of Warcraft” and other games. But that document does not present evidence that terrorists were participating in the games.

Still, the intelligence agencies found other benefits in infiltrating these online worlds. According to the minutes of a January 2009 meeting, GCHQ’s “network gaming exploitation team” had identified engineers, embassy drivers, scientists and other foreign intelligence operatives to be World of Warcraft players - potential targets for recruitment as agents.

At Menwith Hill, a Royal Air Force base in the Yorkshire countryside that the National Security Agency has long used as an outpost to intercept global communications, U.S. and British intelligence operatives started an effort in 2008 to begin collecting data from World of Warcraft.

One National Security Agency document said that the World of Warcraft monitoring “continues to uncover potential Sigint value by identifying accounts, characters and guilds related to Islamic extremist groups, nuclear proliferation and arms dealing.” In other words, targets of interest appeared to be playing the fantasy game, though the document does not indicate that they were doing so for any nefarious purposes. A British document from later that year said that GCHQ had “successfully been able to get the discussions between different game players on Xbox Live.”

By 2009, the collection was extensive. One document says that while GCHQ was testing its ability to spy on Second Life in real time, British intelligence officers vacuumed up three days’ worth of Second Life chat, instant message and financial transaction data, totaling 176,677 lines of data, which included the content of the communications.

For their part, players have openly worried that the National Security Agency might be watching them.

In one World of Warcraft discussion thread, begun just days after the first Snowden revelations appeared in the news media in June, a human death knight with the username “Crrassus” asked whether the National Security Agency might be reading game chat logs.

“If they ever read these forums,” wrote a goblin priest with the username “Diaya,” “they would realize they were wasting” their time.

Information for this article was contributed by Andrew W. Lehren. Justin Elliot is a reporter for Pro-Publica.

Front Section, Pages 1 on 12/10/2013