The iPhone may be vulnerable to hackers due to a flaw in its web browser, according to a security firm, which said it was able to hack into the gadget.

Baltimore-based Independent Security Evaluators, which tests its clients' computer security by hacking it, said on Monday that three employees found a way to take control of iPhones.

Charles Miller, principal security analyst at the firm, said a security weakness allows someone to take control of the iPhone's Safari web browser and see other applications on the device.

The security consultants, who took about a week and a half to work out the move, said they were able to take control of an iPhone and make calls or send text messages, as well as access e-mails, voice-mail, address books and call and web browsing history.

Miller said Apple could avoid the risk by eliminating links between the browser and other applications.

"It turns out that on the iPhone there are probably some basic things they could have done that would have made it better," said Miller.

The claim comes more than three weeks after Apple and AT&T started selling the iPhone, which includes a music and video player as well as a web browser. As many as 700,000 iPhones were sold on the first weekend after the June 29 launch.

Days after launch, a well-known hacker Jon Johansen, claimed to have overcome restrictions on the iPhone, allowing highly technical users to bypass AT&T's network to use the phone's Internet and music features.

While cell phones have not historically been as vulnerable to attack as desktop computers, some experts worry that phones take on greater risks as they add more computer-like features.

Miller said he had not looked into security on other mobile phones to see how they compare to the iPhone, but said the more complex a system is, the greater the likelihood is that it will have problems.