Security experts warned yesterday that cyber-crooks are increasingly targeting online gamers with scams aiming to steal money.

Malware creators are going after the log-in details needed to install and access online games.

The criminals are trying to rob players of virtual assets obtained in the games, such as 'money' that players can use to buy weapons and goods, according to security firm Panda Software.

Given the effort required to obtain these items, there are many people prepared to pay for them as an easy way to reach higher levels and increase their reputations.

As a result, the virtual economy of the game translates into real profits for the cyber-crook, even more so with new games that allow real-world funds to be transferred into the game for use in the virtual world.

According to Panda, the malware that most frequently affects games are Trojans. In one example the Lineage virus steals player log-in details, allowing another player to steal virtual money to buy weapons, privileges or abilities within the game.

In another case, the different variations of the Legmir Trojan target players of Legend of Mir to steal their passwords.

Gaobot and its variants, although more widely known for their bot characteristics, also try to get in on the act, stealing the CD keys of several games and spreading to new victims.

They also open a backdoor on infected computers, making them vulnerable to future attacks. In addition, World of Warcraft players could be affected by Trj/WoW.

Luis Corrons, director of Panda Software Labs, said: "The new financial motivation for malware creators has led cyber-criminals to turn to selling virtual assets for potential returns.

"It is important to consider the damage that this malware, which allows unauthorised users to play using stolen log-in details or CD keys, represents for game developers.

"If companies block access to the key to prevent the fraud, legitimate users will also be blocked. This may cause subsequent confusion, annoyance or a negative impression of the company."