In the latest revelations to come from documents released by ex-NSA agent Edward Snowden, it has been revealed by the Guardian newspaper that the NSA planted agents in the online game of World of Warcraft to monitor players for ‘terrorist’ activity.

It is thought that the NSA believed people of interest to the national security firm could be using the MMORPG to communicate with each other secretly.

The document uncovered, called Exploiting Terrorist Use of Games & Virtual Environment, also reveals that agents were actively present in games such as Second Life and some Xbox games, as Xbox Live was eventually considered as a possible means for terrorist communication.

"Terrorists use online games – but perhaps not for their amusement," it said. "They are suspected of using them to communicate secretly and to transfer funds."

"Al-Qaida terrorist target selectors and … have been found associated with Xbox Live, Second Life, World of Warcraft, and other GVEs [Games and Virtual Environments]," the document said.

"Other targets include Chinese hackers, an Iranian nuclear scientist, Hizballah, and Hamas members."

However, the data used to collect evidence on suspected terrorists using video games was inconclusive, as it was not determined if it was just a person in the same internet café who was gaming, or that if the PC being used was just used to play video games in the past but was not being used at the time of suspicion.

The document also shows that the NSA tried to recruit gamers to help with the project.

Blizzard, the company behind World of Warcraft, has said that they were "unaware of any surveillance taking place," and never gave the NSA permission to infiltrate the game.