The head of the main opposition People Power Party (PPP) on Thursday stressed the need to maintain caution in approaching President Moon Jae-in's proposal of seeking a declaration to formally end the Korean War.

"There needs to be a cautious approach on the end-of-war declaration proposed by the Moon Jae-in administration, which has been reciprocated conditionally by North Korea," PPP Chairman Lee Jun-seok said during a supreme council meeting of the party.

Last week, Moon proposed in a speech to the United Nations General Assembly that the two Koreas and the United States, possibly joined by China, declare a formal end to the 1950-53 war.

The North in response has expressed a willingness to discuss such a declaration on the condition that Seoul ensures mutual respect.

North Korean leader Kim Jong-un on Wednesday also urged Seoul to drop its "double-dealing attitude" first before seeking a declaration to formally end the Korean War, saying it is up to Seoul to determine the future trajectory of inter-Korean ties.

The two Koreas are still technically at war, as the 1950-53 Korean War ended in a cease-fire, not a peace treaty.

Lee, who recently traveled to the US and met with senior administration officials and think tank representatives, stated that Korean Peninsula observers in the US "have expressed a substantial amount of concerns" on an end-of-war declaration that is not predicated on a denuclearization agreement.

On the principle of "mutual trust" demanded by Kim Yo-jong, the sister of the North's leader, Lee argued the North is essentially demanding the South recognize Pyongyang's nuclear status to justify its possession of nuclear weapons.

The opposition chief stressed that an additional inter-Korean summit or an end-of-war declaration preconditioned with the understanding of such "mutual trust" could end up with a result in which Seoul essentially recognizes Pyongyang as a nuclear power. (Yonhap)