Security experts have found what is believed to be the first outbreak of the 'Cabir' mobile phone virus in the 'wild'.
Singapore mobile phone users have been targeted by the worm, which infects phones using the Symbian operating system and spreads over Bluetooth, according to anti-virus firm F-Secure.
Cabir was first discovered in June 2004 after international virus writing group 29A sent the unreleased 'proof-of-concept' sample to AV firms.
The worm has not yet seriously infected mobiles, but does drain battery power considerably while trying to infect other Bluetooth enabled handsets within a 30-metre radius.
'It's a proof of concept virus at this stage, although some people are complaining on internet chatrooms about file losses,' said Mikko Hypponen, F-Secure's director of anti-virus research.
'Future variants could have more worrying characteristics, but at this stage it's fairly isolated.'
But Cabir can only spread through mobile phones that have Bluetooth connectivity switched on and when users accept the file.
Other viruses such as Duts have been written to infect PocketPC mobile devices and last month Brador, a backdoor flaw, was found, which gives cybercriminals full, invisible access to smartphones, meaning they can surf the internet or make calls.