WASHINGTON - EARLIER this year, one animated character in Second Life, a popular online fantasy world, allegedly raped another character.

Some Internet bloggers dismissed the simulated attack as nothing more than digital fiction. But police in Belgium, according to newspapers there, opened an investigation into whether a crime had been committed.

Then last month, the authorities in Germany announced they were looking into a separate incident involving virtual abuse in Second Life after receiving pictures of an animated child character engaging in simulated sex with an animated adult figure.

As recent advances in Internet technology have spurred millions of users to build and explore new digital worlds, they are testing the long-held notions of what is criminal and whether law enforcement should patrol the digital frontier.

'People have an interest in their property and the integrity of their person. But in virtual reality, these interests are not tangible but built from intangible data and software,' said Professor Greg Lastowka of the Rutgers School of Law at Camden, New Jersey.

Some virtual activities clearly violate the law, like trafficking in stolen credit card numbers, he said. Others, like virtual muggings and sex crimes, are harder to define, though they may cause real-life anguish for users.

In World of Warcraft, the most popular online game with an estimated eight million participants, some regions of the fantasy domain have grown so lawless that players say they fear to brave them alone. Gangs of animated characters have repeatedly preyed upon lone travellers, killing them and making off with their virtual belongings.

Two years ago, the Japanese authorities arrested a man for carrying out virtual muggings in another popular game, Lineage II, and then selling the virtual loot for real money.

Second Life, where more than six million people have registered to create characters called avatars that socialise with other characters, might trump them all with its breadth of creativity and interaction.

US presidential hopeful John Edwards has opened a virtual campaign headquarters. Reuters and other news agencies have set up virtual bureaus. On May 22, the Maldives became the first country to open an embassy in Second Life, with Sweden following this week.

About 15 per cent of the properties on the site - space on computer servers that appear as parcels of land -- have been flagged as having mature material. In some locations, avatars act out drug use, child abuse, rape and various forms of sadomasochism.

'This is the double-edged sword of the wonderful creativity in Second Life,' said Mr Julian Dibbell, a prominent commentator on digital culture.

The question of what is criminal in virtual reality is complicated by disagreements among countries over what is legal even in real life. For example, virtual renderings of child abuse are not a crime in the US but are considered illegal pornography in some European countries, including Germany.

After the German authorities began their investigation, Linden Labs, which operates Second Life, said it was cooperating with law enforcement and had banned two participants in the incident, a 54-year-old man and a 27-year-old woman.

Mr Philip Rosedale, the founder and chief executive of Linden Labs, said in an interview that Second Life activities should be governed by real-life laws for the time being.

'In the ideal case, the people who are in Second Life should think of themselves as citizens of this new place and not citizens of their countries,' he said.

Washington Post