SEOUL, JULY 2 -- Ruling party chairman Roh Tae Woo, pressing his policy of political conciliation, dropped in without warning today on a startled opposition party president Kim Young Sam.

"You should have notified me in advance," Kim told Roh, who had to wait about 10 minutes at the headquarters of the Reunification Democratic Party while Kim was summoned from a nearby office.

Roh apologized and said, "I came here to see you and do whatever I can to help you." Roh also told Kim the ruling party is "ready to become an opposition party" if it loses an upcoming election.

The surprise visit appeared to be aimed at impressing the South Korean public with government determination to push ahead with political reforms approved this week by President Chun Doo Hwan. The key reform is direct presidential elections.

What Roh did was virtually unheard-of here. Meetings between top-level political leaders are normally set up days in advance, with newspapers reporting in detail on the arrangements.

Roh's political stock has soared in recent days, as many South Koreans see him as the driving force in pushing the government to accept the popular reforms. He is widely expected to run for the presidency.

"He's really trying to play the politician," said one western diplomat, referring to Roh, a retired Army general. "He's breaking the ice with the opposition in a dramatic way."

The meeting lasted about 15 minutes. The two men agreed to meet again and urge their senior staff members to begin contacts next week on drafting a new constitution.

Kim reiterated demands that political prisoners be released and that the government restore the political rights of fellow opposition leader Kim Dae Jung. The government has agreed to them in principle but has yet to act.

{In an interview with the Los Angeles Times, Kim Dae Jung said Thursday that democracy was not yet assured, and warned that the government could still resort to oppression. Kim also warned that democracy, if achieved, would bring new problems.}

The opposition and the government are now working on drafts of a new constitution, with a target date of mid-July. Negotiations will then follow toward producing a single document, which will be submitted to the National Assembly.

In another development today, government party officials said they are considering measures to heal the scars left by a bloody uprising in the southern city of Kwangju in May 1980.

More than 200 people were killed after Chun ordered Army troops into the city to quell demonstrations there. The incident is considered to be the deepest blot on the legitimacy of the Chun government.

Many South Koreans feel the government has never given an adequate accounting of Kwangju. People in the opposition hold Chun directly responsible for the deaths.

"Our party has reached a consensus that we have to view the Kwangju incident in the right way as our party is implementing substantive democratization measures for national harmony," the semiofficial Yonhap News Agency quoted party spokesman Kim Jung Nam as saying today.

Among the measures under consideration, the agency said, are compensation for the families of the victims, construction of a memorial tower and permission for an official memorial ceremony.

Kim Young Sam today declined comment on the proposed measures. But he said that "the souls {of the Kwangju victims} will feel compensated only when there is democracy."

Kim spent most of the afternoon visiting jailed political prisoners, as part of a schedule that appears to be the start of a presidential campaign. He spent yesterday visiting hospitals to comfort injured students and riot police.

His meeting with Roh was the lead story in the South Korean afternoon newspapers today, and he was followed by photographers when he visited the Yong Dong Po and the West Gate prisons.

Among the political prisoners Kim saw today were about a dozen people, including a vice president of the opposition party, whom police have charged with masterminding a huge street rally June 10.

South Korean cities remained quiet today but Korean news media reported that about 50 radical students fought police briefly with firebombs and rocks in southwestern Seoul last night.