The Cabir mobile phone virus has finally spread as far at the US, and has been spotted on a handset for sale in a shop in California.

The virus, which is spread from handset to handset by Bluetooth, has spread slowly into 12 countries. It was spotted on a handset in a store in California last week, according to Mikko Hypponen, director of security company F-Secure, who told Reuters that the store owner's phone had also been infected.

Infected phones display the message 'Caribe' when turned on, and the worm then looks for other Bluetooth connected handsets nearby that will allow it to spread.

The biggest impact of the virus, which has around 15 variations so far, is that it drains mobile phone batteries. Cabir was discovered in the wild in August last year, and has spread gradually since then.

Earlier this month IBM predicted a surge in viruses targeting mobiles this year, as Cabir is used by copycat virus writers to create an epidemic.

Big Blue also warned that viruses would target embedded computers, including car and satellite communication systems.