An analyst is urging companies to stop staff from using portable storage devices such as iPod because they can be used to introduce malicious software (malware), or to steal corporate data.

Analyst house Gartner has issued a report in which it claims: "Portable storage products can bypass perimeter defences like firewalls and antivirus at the mailserver, and introduce malware such as Trojans or viruses onto company networks."

Devices mentioned include "disk-based MP3 players, such as Apple's iPod, and digital cameras with smart media cards, memory sticks, compact flash and other memory media".

Gartner also says such devices can be used to steal company data. The small size of portable devices means they can be easily misplaced or stolen, it adds.

"Businesses must ensure that the right procedures and technologies are adopted to securely manage the use of portable storage devices like USB keychain drives. This will help to limit damage from malicious code, loss of proprietary information or intellectual property, and consequent lawsuits and loss of reputation," the report stated.