The Dutch supreme court has found a man guilty of theft after he forced a 13-year-old boy to give up a virtual mask and amulet during play of the online game RuneScape.

The Netherlands' highest court said that forcing the boy to surrender the objects online amounted to a real-world theft. The court ruled that the victim owned the virtual objects because of the amount of time and energy he invested in them. The allegations referred to an incident in 2007.

The court said that the defendant, who is now 19 or 20, beat up the then-13-year-old boy with and threatened him with a knife in real life to make him drop the objects in the fantasy game. The defendant, who has not been named, was guilty of the online theft and was ordered to perform 144 hours of community service.

The court heard that the defendant and another youth beat and kicked the boy and threatened him until he agreed to log on to the game and drop the objects.

RuneScape is an online multiplayer adventure game with more 175 million registered accounts signed up to it.