A Web site in which users travel through a virtual world in the guise of an invented character is under police investigation over claims of online sexual abuse.
Some users of the site claim they are so emotionally involved that attacks on "their" avatars leave them traumatized and upset. They term the experience "online rape."
Experts believe that those misusing the site in Britain, where more than 100,000 "residents" have logged on in the past six months, could be vulnerable under laws prohibiting harassment and the sending of malicious messages.
"The terms and conditions of joining 'Second Life' make it clear there is a prohibition on stalking, abusing or harassing other users," said Graham Smith, a partner at the London solicitors Bird & Bird and co-author of the book "Internet Law and Regulation."
"There is clearly no consent to harassment or anything of the sort — quite the opposite, it's off limits. So that brings the potential to apply real-world laws."
Users of "Second Life," run by the San Francisco company Linden Lab, design their own avatars and travel around the virtual world — going on vacation, meeting each other at nightclubs, shopping and buying land and developing it.
A high proportion of the avatars are slim big-chested women and enormously well-endowed men. Cyber-sex is one of the most popular activities: one common practice is for naked male characters to rub against females.
Some users — the site claims it has 6 million accounts worldwide — spend so much time on it that they become almost as emotionally involved as they would be in the real world.
The site has already raised concerns over child protection, with police in Germany investigating its alleged use by pedophiles to exchange obscene images.
A Linden Lab spokesman said "Second Life" had "absolutely zero tolerance for depictions of child pornography" and would cooperate with the police.