The probe follows claims that Apple traced and stored geographical data from its mobile device users in countries such as France and Germany.

The Korea Communications Commission said it had sent a list of questions asking Apple Korea to clarify why location data was collected from mobile device users and how frequently such data was recorded.

Apple is also required to explain why such information is not encrypted, whether device users have a choice over data deletion or data storage, and whether such data is stored on its servers, it said.

British security researchers have said the position-logging feature is contained in iOS 4, the operating system for the iPhone and iPad released in June.

They said iOS 4-equipped iPhones and iPads store latitude and longitude coordinates along with a time stamp, probably through cell-tower triangulation.

They noted that cellphone companies typically have access to this data but it is not usually stored on a mobile device itself.

The Wall Street Journal reported that Google's Android smartphones also regularly transmit their locations back to Google.

KT, the second-biggest mobile carrier in South Korea, has sold more than two million iPhones since November 2009.