South Korean President Yoon Suk Yeol called Thursday for peaceful unification with North Korea "based on freedom and democracy."
Yoon also called for an official dialogue channel to address issues between the divided Koreas, Seoul-based Yonhap News reported.
"The freedom we enjoy must be extended to the frozen kingdom of the North," he told an event to mark Liberation Day.
"Only when a unified, free and democratic nation rightfully owned by the people is established across the entire Korean Peninsula will we finally have complete liberation," he added.
South and North Korea have been divided since the 1950s following the defeat of Japan during World War II, when the Korean War ended in an armistice rather than a peace treaty.
Over the years, however, the two sides had set up communication channels and sealed pacts to promote trade and military agreements.
But in recent months, nearly all such pacts and agreements have ended as the two sides ramped up rival military activities.
While Seoul has closed ranks with the US and Japan, Pyongyang has established closer ties with Russia.
Yoon's proposal towards unification with the North came amid controversy, as some independence fighter groups and opposition lawmakers boycotted the official ceremony.
They protested the appointment of a director at the national independence museum who is accused of justifying Japan's colonial rule over the Korean Peninsula.
