The German government has warned that Apple's iPhone, iPad and iPod Touch have potentially serious security problems. Computer security experts have repeatedly pointed out the vulnerabilities of the iPhone to hacking, but Apple maintains the concerns are groundless as long as users keep their devices in locked mode.

The German warning comes on the heels of an alert by Symantec, the largest maker of PC security software. Some 3 million people in Korea own smartphones, including iPhones.

The Federal Office for Information Security on Wednesday said Apple's iOS operating system has "two critical weak points for which no patch exists." "This allows potential attackers access to the complete system, including administrator rights." The federal agency warned Apple device users against using PDF files on their mobile devices and advised them only to use trustworthy websites until Apple publishes a software update.

Apple's software enabling users to view PDF files are vulnerable to attacks. They could become infected if the Safari Internet browser is used to view a PDF file containing a malignant code. The German agency also warned that hackers could obtain passwords as well as information from e-mails, text messages and schedules and even tap into phone calls. It said hackers could launch attacks soon using the iPhone's weaknesses.

In response Apple promised to come up with a solution soon.

So far Apple has enjoyed a reputation as being less vulnerable to bugs than devices that run Microsoft software, and Apple said the iPhone could not be infected with malignant codes through PDF files since the devices are incapable of multi-tasking. The company also claimed iPhone applications are sold only through its own websites under strict control, making it impossible for infected contents to be downloaded. As a result, no security programs developed by other companies are sold in Apple's online stores. One Internet security expert said, "Apple will have to make major changes to its security policy."

The popular BlackBerry smartphones made by Canada's Research In Motion have also been the target of security warnings by governments around the world. The EU Council said recently that its decision not to adopt BlackBerry smartphones for staff was due to potential security threats.

Earlier, Saudi Arabia, the United Arab Emirates, China, India and Kuwait also banned the BlackBerry messaging service due to what they claimed were security threats. Google's Android and Microsoft's Windows smartphones are also vulnerable to hacking. Android smartphones are classified as the most vulnerable to attacks, since anyone can upload and download applications. SK Telecom issued a hacking alert to Android phone users on Twitter saying it discovered a virus targeting them.