Symantec, McAfee, and a swarm of rival security software makers are beginning to ship a wider number of products designed specifically to protect smartphones, as smarter handhelds find their way into enterprises.

Sales of smartphones grew by roughly 66 percent to 81m units in 2006, according to estimates published by researchers Gartner.

The devices are popular in Asia and Europe, with market watchers predicting that a vast majority of large US companies will distribute at least a handful of the handhelds to workers before the end of 2007. Many will buy hundreds.

Based on the growing proliferation and complexity of smartphones – which offer wireless e-mail, internet access, and mobile business applications along with their calling functions - security applications vendors see range of opportunities to carry the same tools they have been selling on the desktop onto the emerging mobile platforms.

On 26 March, Symantec launched its new set of security applications for smartphones running on Microsoft's Windows Mobile operating system.

In addition to adding Microsoft's flagship device operating system to its stable, which also includes coverage for high-end handhelds based on software made by Palm and Symbian, the package introduces new virtual private network (VPN), data encryption, anti-spam features.

Symantec and its rivals are betting that companies will soon want to license robust suites of mobile security applications just as they buy many forms of desktop software today.

"Beyond the protection of the environment itself, people are already going a step further; they already know that they need to protect bits that make up the data now that some of the most valuable data a company can have is on the hips of c-level executives around the globe," said Paul Miller, managing director for Mobile Security at Symantec.

Experts admit that few mobile viruses have plagued smartphone users so far, despite the known existence of a sizeable number of proof-of-concept attacks, but some predict that handheld malware is coming.