A South Korean intelligence official says North Korea is believed to have stolen the personal information of an estimated one-point-six million South Korean officials through Internet hacking over the past five years.

The source said the National Intelligence Service (NIS) and other authorities have looked into a multitude of recent personal data theft incidents and have traced a number of the hacking routes to North Korea.

The main targets hacked were Web sites of South Korean security organizations and university alumni groups. The NIS found that the North had databased resident registration numbers, addresses, phone numbers and email addresses of South Korean officials.

The intelligence official said North Korea used the email addresses of key South Korean officials to hack into government Web sites and to steal government documents.

The NIS also implicated the North for the recent distributed denial-of-service (DDoS) cyber attacks.