Ju Chul-ki, South Korean secretary for foreign affairs and national security, made the comments in a speech to an international conference hosted by the Institute for National Security Strategy, Yonhap News Agency reported Friday.
Ju noted that South Korea, the United States, China, Japan and Russia have been trying to restart talks with Pyongyang since 2012 over its nuclear weapons program.
"Prior to the resumption, however, North Korea should pledge to remove its nuclear weapons and come up with detailed action plans on how it will implement this," Ju said.
Because of sanctions imposed on North Korea for its refusal to end its nuclear program, Ju said no county "would ever invest" in the communist country.
If North Korea ended nuclear development, the official said, Seoul and Western countries would help rebuild the country's economy.
"We will make every effort to create a new Korean peninsula based upon a strong security posture and deterrence," Ju added. "North Korea's change is a must and inevitable."