A man who hacked into accounts to steal virtual characters and their possessions on one of the world’s biggest multi-player online games has been arrested.

In what experts believe is the first case of its kind in Britain, the man obtained log-in details for RuneScape, a web-based role playing game with more than ten million members, to steal their “virtual” characters.

Players in the game have often spent years creating their online characters by completing set tasks and activities.

Police believe that password details were obtained through a so-called phishing scam where a fake internet page tricks people into handing over their personal information.

Officers from Central Police e-Crime Unit arrested the man last Tuesday on suspicion of a number of computer misuse offences. The man, from the Avon and Somerset area and who has not been named, accepted a police caution.

Games industry analysts and experts said that the case was unprecedented in this country and represented a legal grey area.

Complaints about people’s identities and possessions being stolen within a game have been made before, but because it exists only in a virtual world it is hard to say whether they are of any real value in the real world.

But a lucrative market has emerged by those who want to buy powerful characters and items within RuneScape and other popular games, such as World of Warcraft.

The resale of characters and their possessions is often against the rules set down by the makers of the games, but there are no criminal laws banning it.

“A bag of gold, a hammer or a sword within a game can be worth thousands of pounds,” said Rob Fahey, games analyst and former editor of gamesindustry.biz. “It’s bizarre, but that’s the 21st century for you.”

The financial rewards on offer have created an underground industry — dubbed gold farming — where players play in slave-like conditions to obtain the items and sell them on.

In China, where the sale of virtual goods for real money has now been banned, two men from Chengdu were arrested last year for the practice. Local media reported that the pair had made around £150,000 in six months through gold farming within World of Warcraft, employing 20 people in the process.

“Our first and only concern is protecting our player community as we know the high value players place on their unique accounts,” said Mark Gerhard, chief executive of Jagex Games, the Cambridge-based company that launched RuneScape in 2001.

“Players invest years of time and effort into developing their RuneScape character so the theft of a RuneScape account shouldn't be treated differently to the theft of any other valuable possessions such as a games console, television or car."

Mr Gerhard said that the company took a zero tolerance approach to hackers and worked with police in Britain and the FBI in America to combat cyber crime internationally. He said that 95 per of the hacking crimes within RuneScape were down to a handful of individuals.

Similar incidents have occurred around the world. Last year, a court in the Netherlands convicted 14 and 15 year old boys after they assaulted another RuneScape player, threatening him with a knife and forcing him to hand over an amulet and a mask within the game. The court set a precedent in that country by saying: “these virtual goods are goods (under Dutch law), so this is theft”.

In South Korea, computer games tournaments are a national obsession with matches taking place in stadiums, and televised nationally. Police in the country report that they receive tens of thousands of complaints on “cyber crimes” a year that have something to do with online gaming.

In Britain, the Police Central e-Crime Unit was set up in September 2008 to target serious and organised online crime. A spokesman for the unit said: “People who seek to destroy others online gaming experience could be committing criminal offences, leaving themselves liable to prosecution. The PCeU will continue to work with the industry and investigate these allegations where appropriate.”