South Korean President Chun Doo Hwan announced today a new formula for reunifying North and South Korea, two countries that have remained divided by war and ideology for 37 years.

In a New Year's policy statement before a special session of the South Korean National Assembly, President Chun, an Army general turned politician, called for talks on the adoption of a pan-Korean constitution, the establishment of a unified system of government and the selection of a nonpartisan legislature.

The announcement, which was broadcast on nationwide television, represented the most sweeping and detailed proposal put forward by South Korea since the end of World War II and the uneasy military standoff that has prevailed between the two countries following the end of the Korean War in 1953.

Knowledgeable observers both here and in Tokyo said that, while the chances of North Korean acceptance of Seoul's bid remained slight, the maneuver primarily was aimed at enhancing the South's international image by displaying its efforts to deal positively with the long-pending national reunification issue.

It was also an attempt on the part of the Chun government to counter a longstanding North Korean proposal for a "confederation" of North and South Korea under which independent government systems on both halves of the peninsula would remain intact, pending the settlement of thorny political issues by a nongovernmental body composed of representatives from both countries and overseas Korean communities.

Seoul has rejected the blueprint of the North Korean government in Pyongyang as an attempt to make all of Korea communist.

As a practical arrangement leading to the reunification of the two Koreas, Chun proposed that North and South organize a consultative body representing residents in both halves of the divided peninsula aimed at thrashing out the terms of a unified constitution.

Explaining the details of the formula, which follows numerous, although less elaborate, past proposals, Chun said, "the most reasonable way to peaceful unification is to adopt a constitution of a unified Korea testifying to the commitment of the entire people and to establish a unified state on the terms and conditions laid down in the constitution."

To pave the way for the drafting of such a constitution, Chun said "the unnatural relations between the South and North that have resulted in self-inflicted injuries must be brought to an end."

He proposed an agreement between North and South on a seven-point interim pact in advance of a constitution and free elections, including a call for each side to:

Appoint a cabinet-level envoy to head a liaison mission in Seoul and Pyongyang, respectively.

Renounce the use of military force or violence and to seek "peaceful dialogue."

Recognize each other's existing political and social institutions and not interfere in each other's internal affairs.

Maintain the existing United Nations armistice agreement that ended the Korean War while working out measures to end the arms race and military confrontation.

Open themselves to various forms of exchange and cooperation such as free travel and the reunion of separated families.

Observers said Seoul's insistence on the maintenance of the U.N. armistice agreement was likely to reduce sharply the chances for Pyongyang's acceptance of the proposal.

North Korea has indicated, in the past, that the withdrawal of the 38,000 American troops stationed in South Korea and the conclusion of a peace treaty between Washington and Pyongyang, excluding Seoul, are prerequisites to any moves toward ultimate reunification.

Following the chaos touched off in South Korea by the assassination of president Park Chung Hee in October 1979, North Korean officials launched new overtures to open talks on reunifying the two countries.

Since Chun came to power in September 1980, however, Pyongyang has reportedly cut off all channels of communication with the South.

Recent efforts to revive unification talks have foundered because the North has refused to recognize the legitimacy of the Chun government.

On Jan. 12 and June 5 last year the South Korean president proposed a summit meeting with North Korean President Kim Il Sung. Pyongyang failed to acknowledge those overtures.

A source close to North Korea in Tokyo said "Pyongyang has no reason to speak with the Chun regime," but that a response on Seoul's new proposals may be expected sometime soon. So far, Pyongyang has remained uncharacteristically silent.

Washington Post Tokyo correspondent Tracy Dahlby contributed to this story.