Security firm F-Secure has launched the fifth iteration of its mobile security software, which tackles what the firm describes as a slow but steady growth in mobile malware.

Smartphones are becoming increasingly sophisticated, and users are storing a large amount of personal and business information on the devices.

"We do not want to overstate the problem or try to create too much hype about it," said Samu Konttinen, vice president of the mobile business unit at F-Secure.

"But the fact is that, wherever there is money to be made, there is crime. People need to protect their most personal computer."

Research conducted by F-Secure suggests that there are more than 400 mobile viruses in circulation. Some of these are simply annoying, such as Skull.D, which locks up the phone with a flashing skull and crossbones on the screen; but others can cause considerable damage.

Konttinen warned that, although 400 viruses may be a tiny figure compared with the millions of PC viruses floating around today, some mobile malware applications are extremely worrying as they can continuously send premium rate texts or deliver email and other personal information to a third party.

Some can even use a phone's GPS system to track the user's movements, and are marketed as legitimate applications as a way for parents to keep track of kids, suspicious partners to uncover infidelities or businesses to audit the use of their mobile phones.

The latest version of F-Secure's mobile security application promises to protect against the misuse of confidential information, spyware, unwanted billing and malware. It also offers a new anti-theft feature with remote lock, and remote wipe and theft control functionality that kicks in as soon as the SIM card is changed, sending the new information to the owner via SMS.

The new system also features a two-layer update mechanism, so updates can be delivered over a data connection when available or via SMS for critical updates.

F-Secure Mobile Security 5 will be available for Symbian S60 third edition devices in December and will be available for Windows Mobile handsets early next year.

The company is looking into developing versions for other platforms such as BlackBerry and iPhone, but no announcements have been made.