Seoul Reconsiders Opening to North. Pyongyang accused of boosting its psychological and political warfare against the South. KOREAN REUNIFICATION: PUTTING ON THE BRAKES

THE South Korean government is having second thoughts about its much vaunted policy of improving relations with North Korea and its communist allies. North Korea has failed to respond to attempts to open a serious dialogue, charges Minister for National Unification Lee Hong Koo. Instead, ``They are increasing their political and psychological warfare'' against the South, the senior official told the Monitor this week.

The government accuses the North Koreans of seeking to encourage the radical activities of anti-government forces in the South. Dissident groups, Mr. Lee says, are intensifying their efforts to overthrow the government of President Roh Tae Woo and ``to push out'' the American presence, particularly the 41,000 United States troops helping to defend the South.

The Roh government denies it is abandoning its ``Northern policy,'' which it once heralded as a hallmark of its rule. But, Lee says carefully, ``We have to adjust the speed of our policy.'' The Seoul government, the official revealed, is also asking Japan and the US to cool their own efforts to open doors with the North. At South Korea's earlier urging, the two allies of the South had lifted restrictions on diplomatic and other contacts. Now, Lee says, ``We are encouraging more caution.''

President Roh initially unveiled the policy with much fanfare in a July 7 speech last year. The Seoul government was responding, in part, to a wave of student protests in favor of opening talks on reunification, an emotionally potent issue here.

The successful holding of democratic elections for president and the legislature, Roh declared then, gave South Korea new confidence to pursue exchanges with its bitter enemy in the North. The new policy included lifting bans on access to North Korean propaganda, permitting travel to the North, and allowing trade. In an October speech to the United Nations, Roh called for summit talks with North Korean President Kim Il Sung and an end to treating each other as enemies.

Since last summer, North-South talks have been held on two tracks - between parliamentary delegations and more recently between the two governments. But both negotiations have failed to move much beyond their initial starting points.

The openings to North Korea have been accompanied by aggressive efforts to open ties with the socialist bloc.

This element of the policy has yielded the most tangible results, as the South has opened diplomatic relations with Hungary and trade ties with China and the Soviet Union. (A Soviet trade office opened in Seoul only last week.) The decision of almost all communist countries to attend last summer's Olympic Games in Seoul, despite a North Korean boycott, was a high point of this diplomacy.

But even this is now coming under review. On Monday, the Federation of Korean Industries suddenly canceled a visit to Moscow of leading businessmen who had been scheduled to leave Friday. Federation officials, according to Korean press reports, said it was a government decision.

Foreign Minister Choi Ho Joong, in a speech this week on the Northern policy, declared, ``We will have to be very cautious in seeking economic cooperation with the Soviet Union and China.''

The Roh administration had sought to use the improvement of ties with the major communist powers to pressure the North into a more flexible stance. According to Lee, Seoul calculated that the reforms pursued by Beijing and Moscow would encourage the tightly controlled dictatorship of Kim II Sung in the North to open up.

Critics have accused the government of overselling the results of this policy, partly for domestic political comsumption. The government denies this charge. But, Lee admits he ``underestimated (the North Korean) capacity to be isolated from the general trend in the international community, particularly in the socialist world.''

The architects of the Northern policy have been under increasing attack from both ends of the political spectrum. ``From the right-wing standpoint, the government is too liberal,'' explains Minister Lee. ``But from some of the dissidents' viewpoint, we're too slow.''

The visit of dissident Rev. Moon Ik Hwan to North Korea on March 25 has clearly strengthened the voice of the right. The government is now considering reversing its easing of restrictions on contact with the North, Minister of Legislation Hyun Hong Choo told the Monitor.

``When we say we will allow North Korean literature ... we didn't say we would allow subversive literature which has the sole aim of overthrowing this government,'' the senior official declares.

This reaction worries some observers, and calls into question the government's ability to move ahead in the difficult rivalry with the North. ``They still don't trust their own people,'' one Western diplomat comments.