Spammers target gamers in massive multiplayer online games by creating characters that send unsolicited ads for items such as extra weapons and playable characters.
The spam companies hire players to collect points and weapons by completing mundane in-game activities, which are then passed on to ‘mules' for sale on third-party sites.
Sony's Norathian Underground Gnome Investigation Team (Nugit) targets such activity, which is banned by all game publishers.
According to Sony Online Entertainment president John Smedley third-party companies make $2 billion (£1.2bn) a year selling virtual items.
"People get very frustrated when they see spam. It's the equivalent of junk mail and you're getting this in-game and it's very frustrating," he said.
Nugit's nine-member team has shut down 295,000 subscription accounts as a result of its in-game detective work.
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