South Korean President Lee Jae Myung pledged to "respect" North Korea's political system and said Seoul would not seek unilateral reunification in a speech to mark Liberation Day.

South Korean President Lee Jae Myung vowed on Friday to "respect" North Korea's political system and build "military trust", a day after Pyongyang said it had no interest in improving relations with Seoul.

In a speech to mark the 80th anniversary of Korea's liberation from Japanese colonial rule, Lee said he would restore the so-called September 19 Comprehensive Military Agreement, a de-escalation measure that halted some military activities at the border between North Korea and South Korea.