Malware writers are using a popular iPhone game to infect PC users.

Researchers at security firm Sophos said that the cyber-criminals have created imitations of the Penguin Panic game laden with malware.

The Trojan packages are disguised as a game for the iPhone in which a small bird leaps between icebergs.

Penguin Panic had been available for the Apple handset for several months prior to the opening of Apple's App Store and was played on 'jail-break' handsets.

The game does not appear to be available on the App Store, Apple's official avenue for distributing iPhone applications. The latest attack, however, claims to offer a desktop PC version of the game.

The attackers use spam messages to spread the game under such titles as 'virtual iPhone games', 'take a break', and 'virtual iPhone toys'. Attached to the message is a .zip archive entitled 'penguin.panic.zip' which contains a Trojan application.

On launching the zip file, the user is infected with 'troj/agent-hny', a recently discovered Trojan downloader classified by Sophos as a low-level threat.

Ironically, the Penguin Panic attack does not affect users of the iPhone or Apple's MacOS X. The Trojan is only a threat for Windows systems.

Users can avoid spam malware attacks by not opening any attachments in unsolicited emails and only downloading games from trusted sites. Many experts also recommend that users maintain updated antivirus software.