The Nokia 3650, 6600, and 6630 are all vulnerable to 52 new trojan viruses, which anti-virus specialist SimWorks says are "cracked" versions of popular Symbian applications such as BitStorm, BugMe!, Cosmic Fighter, 3D Motoracer and SplashID. Series 60 phones using Symbian OS v6.1 or newer are at risk, SimWorks has found.

"This is a significant development as until now we've usually found mobile trojans two or three at a time at the most. It would be easy for a malware writer to create 1 trojan and give it 52 different names however this is not the case here where we have 52 separately cracked and infected applications. Somebody has gone to an awful lot of time and effort to turn these out," sais SimWorks CEO Aaron Davidson.

"Previous mobile viruses have either been able to spread but cause no harm or alternatively have been able cause significant harm but not able to spread. It may be that producing large numbers of harmful trojans such as those we discovered today is a reaction by the writers to their inability to produce destructive viruses that can effectively spread. Obviously by producing large numbers of these things you greatly improve the odds of someone actually downloading and installing them."

"Until reports are received of these trojans in the wild, however, there is little risk to end users," Davidson added.