Dissident's Trip North Upsets Seoul. PROVOCATIVE JOURNEY

THE visit of a leading South Korean dissident to North Korea has sparked a sharp political confrontation. The Seoul government has linked the trip to an alleged left-wing plot to overthrow the South's fledgling democratic system. Dissident forces fear that right-wing elements are seeking to use the incident to suppress the progress of democracy. And the moderate opposition parties fear they are being squeezed between the extremes at the left and right.

The March 25 arrival in Pyongyang of Rev. Moon Ik Hwan and two fellow dissidents surprised South Korea.

During the 10-day visit, the longtime antigovernment activist held lengthy meetings with communist North Korean leader Kim Il Sung and issued a joint statement on principles for reunification of the two Koreas.

Rev. Moon, now in Tokyo on his way home, defended his visit as an effort to advance the dialogue South Korean President Roh Tae Woo has promoted as a key government policy initiative.

In a barrage of statements, the government has assaulted the dissident for aiding North Korean attempts to divide opinion in the South. Playing on conservative fears of communism, the government has encouraged the media to publicize the visit, including broadcasting footage of Rev. Moon embracing Kim Il Sung. The South Korean government has declared its intention to arrest Moon upon his return.

Critics accuse the government of a double standard, pointing to the visit of Korean industrialist Chung Ju-yong to Pyongyang in January which was celebrated as a breakthrough in relations. The government has responded that all contacts must be approved in advance, as that was.

South Korean opposition parties have supported this position, criticizing the dissident cleric for acting secretly. The visit has placed the opposition on the defensive, trying to avoid the appearance of supporting pro-North actions.

But opposition circles are also fearful the government is using this as an opportunity to set back the process of democratic reforms. The Korean central intelligence agency ``is recovering its once-lost influence,'' charges National Assemblyman Cho Se Hyong from the Party for Peace and Democracy.

Police arrested several dissident leaders earlier this week for alleged involvement in the trip. A task force has been created to investigate, focusing on the Chonminnyon, the National Coalition for Democratic Movement, the leading dissident group to which Rev. Moon is allied.

Kim Keun Tae, a leading dissident, accuses the government of ``trying to use this incident to get of a political jam.'' Mr. Kim, who was held for two days by police for questioning, says the Roh government is trying to divert attention from the legislature's investigations of its ties to the preceding unpopular regime of Chun Doo Hwan and the Army's killing of hundreds of antigovernment demonstrators in 1980.

Certain elements of the government and the ruling party have been almost gleeful about the Moon visit, which allows them to link aspects of anti-government activity to the North. They said that the trip is part of a pattern of leftist activity, including student demonstrations, labor unrest, and dissident political activity. ``Leftists seem to have infiltrated by and large into schools, work places, and other segments of our society,'' a senior government official told Korean reporters. Such rhetoric has been used to justify recent deployment of riot police to break militant strikes.

Such fears, which most analysts consider highly exaggerated, are widely current among Korean military figures and within the ruling Democratic Justice Party.

Recently, Western diplomatic sources say, such right-wing circles have been critical of President Roh for his policy of opening contacts with communist countries, for seeking dialogue with the North, and for being unwilling to suppress violent protest at home. In the view of these circles, a Western diplomat says, ``all leftism is bad, and all leftism comes from north Korea.''

For the right, Moon's trip is being used ``as a means of strengthening their power base,'' says veteran political commentator Park Kuon Son. The visit, he says, is ``a case of the extreme left wing helping the extreme right.''

President Roh is credited, even by his critics, with trying to weave a difficult path between those extremes.

``Roh Tae Woo is actually fighting a two-front war,'' says Assemblyman Cho. ``One against the opposition and dissidents and the other against in-house rightists.''