The Youth Care Foundation (Stiftelsen Ungdomsvård), which works to advocate active alternatives to gaming, described the game as "the cocaine of the computer games world".
The foundation's report is as yet unpublished and is based on the experiences of gamers and their parents who have been in contact with the group.
"There is not a single case of game addiction that we have worked with in which World of Warcraft has not played a part," according to Sven Rollenhagen at the foundation to the newspaper Metro.
World of Warcraft is an online fantasy game, which according to the Game Over treatment centre in Linköping in central Sweden are the types of games which carry the highest risk of addiction.
The Local reported in November 2008 that a boy in Laholm, southern Sweden had been admitted to hospital after collapsing following a 20-hour World of Warcraft binge.
The foundation, founded in 1991, works with all types of addiction and since 2007 this has included computer games. The group runs the help website spelfritt.se.
Story continues below…
Of the 2,000 calls received by the foundation in 2007, 170 concerned computer games, Metro reports.
According to the Swedish National Institute of Public Health (Folkhälsoinstitutet), the problem with computer game addiction is large in Sweden although there is currently no medical diagnosis of the condition.