The warning follows the launch of the first mainstream micro-payment service for mobile phone users by Vodafone. Micro-payments cover the £5-or-less spending bracket not served by credit or debit cards.
As mobile phones become more powerful, users will be able to download software applications from the Internet, such as e-mail or a company's directory, making them an attractive target for hackers.
In recent years there have been reports of viruses specifically targeting mobile phones in Europe.
Graham Titterington, senior consultant at analyst firm Ovum, said hackers could create software viruses and use computers to randomly dial thousands of mobile phone numbers, some of which may download rogue software.
A Trojan horse - a program that appears legitimate, but performs some illicit activity when it is run - could be used to locate password information or make the system more vulnerable to entry. A hacker could use it to siphon off small amounts of money from thousands of accounts.
Alternatively, the virus could simply destroy programs or delete data from the phone's hard disc.
This kind of threat could become a problem for micro-payment users when next generation phone services hit the market, said Titterington. "The more functionality you have the more vigilant you have to become," he warned.
Vodafone said it regularly reviews its security measures and will update them to deal with new threats when necessary.