The first example of a mobile phone virus disrupting a company has appeared in Scandanvia, according to security vendor F-Secure.

An unidentified small company was laid low after the virus appeared on an employee's phone and rapidly spread through short-range Bluetooth to others' phones. The outbreak lasted about a day as dozens of employees received the virus and about 20 of them opened it on their phones, according to a blog entry on F-Secure's site.

Viruses are becoming more common on mobile phones, but people remain largely unaware of the fact, aiding its spread. The virus in this case, Commwarrior.B, shows up as an attachment to an MMS message or via Bluetooth. In an MMS, the user is asked if they want to open the attachment, and in Bluetooth they are asked if they want to accept it and then whether they want to run it. Mobile viruses typically identify themselves as something appealing, such as games or anti-virus utilities.

"People probably take for granted that it's just a joke program, because viruses are not that common in the mobile world," said anti-virus researcher at F-Secure, Ero Carrera.

When the virus gets on to a phone, it immediately tries to spread itself by scanning the local area for Bluetooth devices with Bluetooth and sending MMS messages to numbers on the phone's contact list. Fortunately the virus in this case does not cause any damage to the phone. The spread was stopped when employees realised what was happening and stopped opening the attachment when it was sent to them.

Some existing mobile phone viruses do cause trouble however, changing icons or preventing users from starting certain applications. "Probably we'll see these cases happen more in the future in communities where people trust each other," Carrera warned.