SEOUL, DEC. 17 (THURSDAY) -- Ruling party candidate Roh Tae Woo, who promised voters he could deliver stability and democracy, won the presidency in South Korea's first direct election in 16 years.

The election was immediately condemned as fraudulent by opposition politicians, longtime dissidents and students, who vowed to take to the streets to protest what they called a crooked voting process. The ruling party said voting was conducted in "exemplary" fashion, while some neutral observers said they had failed to detect widespread cheating.

Roh's victory, which was expected to be certified later today, would be a stunning accomplishment for a former general with no political experience who helped President Chun Doo Hwan come to power in a 1979 military coup. Roh managed to reshape his image from coup maker to conciliator in the minds of many voters, while profiting from the inability of antigovernment forces to field a single candidate.

Roh -- pronounced "no" -- also succeeded in distancing himself from the unpopular Chun by taking the initiative this summer to call for direct elections after widespread antigovernment protests. But his victory, with less than 40 percent of the popular vote, together with the charges of illegalities and a strongly regional pattern of voting, appeared to guarantee at least a period of instability.

In a statement released this morning, Roh said that his "safe margin" of victory will help him bring about reconciliation.

"My first priority will be focused on quickly healing the many wounds and pains our society has suffered," he said. He called the result "a victory of the great ordinary people who chose democratic reform with stability and national development without chaos."

With 83 percent of the vote counted, Roh was leading with 37 percent. Opposition leaders Kim Young Sam and Kim Dae Jung had polled 26.7 and 26.1 percent, respectively, while former premier Kim Jong Pil had garnered 8 percent and minor candidates the rest.

A record 89 percent of this nation's 26 million eligible voters cast ballots yesterday on a cold and sunny day, apparently relishing the chance to have a say in their future for the first time since 1971.

Ku Chang Rim, Roh's spokesman, said that most Koreans will accept the election as generally fair and will not support protesters' efforts to derail the transition of power.

Referring to students and opposition groups who have called protest rallies for today and Friday, Ku said, "The important thing this time is that they would not get the sympathy of middle-class people."

Chun has promised to become the first chief executive in South Korea's history to step down voluntarily, breaking a tradition of coups and assassination. Roh would succeed him in February.

But supporters of Kim Dae Jung and Kim Young Sam vowed yesterday not to accept the results of the vote. South Korea seemed certain to be facing another round of demonstrations and street clashes, the outcome of which could depend on middle-class perceptions of the fairness of the vote.

Even before the vote, the government had signaled its intention to crack down hard on protesters once Roh was declared winner.

The National Coalition for a Democratic Constitution, which led the protests in June that eventually forced Chun to allow this election, immediately rejected the election results.

"We denounce the all-out fraud-ridden election conducted by the present regime," the coalition of religious and dissident groups said in a statement. "We declare that the responsibility for all the unfortunate incidents that may ensue following the voting and counting lies entirely with the present regime."

Kim Dae Jung called the election a "complete mockery." He said: "This election has been thoroughly riddled with fraud, irregularities and illegalities. The scope and level of election infractions have been truly unprecedented in Korea's modern history."

Kim also lost in the nation's last election in 1971. His aides labeled yesterday's election "systematically fraudulent" even before polls closed. They said their members had observed multiple voting by single voters, the production of false ballots, switching of entire ballot boxes and other illegal practices.

"The election process and the result were rigged," said Kim Dae Jung aide Han Hya Gap this morning. "People will do their job . . . . People will not stay silent."

Kim Young Sam's campaign chairman, Kim Jae Kwang, said his party would join in resisting the election results.

"We believe three million votes have been stolen," he said. "We declare the election results invalid."

Roh Tae Woo was leading by a margin of 2 million votes out of 19 million counted.

Other observers offered a more mixed picture. In most parts of the nation, Koreans lined up peacefully to vote and poll-watchers appeared to be carrying out their tasks conscientiously.

{In Washington, State Department spokeswoman Phyllis Oakley said the elections "appear to have been conducted in an orderly manner, overall." She declined further comment.}

But there were hundreds of instances and reports of abuses or suspicious activities by local officials, all of whom are appointed by Seoul and the ruling party.

In the tiny village of Chun Hyun-ri south of Seoul, for example, Kim Young Sam supporter Yu Pyong Ik said he caught a local village chief with 15 fake registration slips that would have permitted 15 phony votes.

In several places, volunteer student poll-watchers reported being beaten up by thugs who they believed were connected to the ruling party.

And there were a handful of apparently suspicious incidents involving the transportation of ballot boxes that remained unexplained this morning.

Steven M. Schneebaum, a Washington lawyer who led a poll-watching effort by the International Human Rights Law Group, said in a preliminary assessment that his delegation had not witnessed widespread cheating. He cautioned that he was speaking only of election day and not of the campaign, which the opposition charged was also marred by vote-buying, manipulation of absentee votes and biased media coverage.

"We saw a few things I didn't like, but by and large we didn't see anything that amounted to fraud," Schneebaum said.

"Administratively, they seemed to be doing what they were supposed to be doing," another lawyer in the group said.

The emerging margin of Roh's victory, which exceeded pollsters' expectations, seemed likely to defuse the cheating issue, at least for some voters.

The split between opposition candidates Kim Dae Jung and Kim Young Sam also appeared likely to weaken their position as they complained about the election.

Many voters noted that cheating could not have been as large an issue if the two Kims had fielded a single candidate, as they had promised throughout the summer.

The election results represented a bitter loss for the opposition, which viewed the race as a chance to "end military rule" after years of struggle. Many voters yesterday expressed anger and disappointment that the two Kims, alternately allies and rivals through the past two decades, could not rise above their ambitions to take advantage of the opportunity.

"The opposition promised to deliver a single candidate, and they didn't deliver," one ruling party official said. "People were very frustrated."

Roh skillfully exploited that frustration, portraying himself as a candidate who could rise above the petty rivalries of opposition factions. Turning the opposition demand for an end to military dictatorship on its head, Roh repeatedly called for an "end to the era of the three Kims."

The ex-general's campaign really began June 29, when he stunned the nation by appearing on television and urging a package of reforms after weeks of antigovernment street protests. Two days later, Chun accepted the package, including direct elections and a freer press.

For the next six months, Roh -- who for seven years had served loyally as Chun's number two in a variety of jobs -- threaded a narrow path between independence and disloyalty. He apologized for past cases of police torture and promised an administration free of corruption, implicitly criticizing the Chun regime in which he served.

Until early this month, opposition leader Kim Young Sam nonetheless seemed to be in a position to win, according to pollsters here. He had positioned himself as the moderate centrist who could promise democracy without threatening the power structure.

But Roh's spokesman, Ku, said Kim was hurt in the last weeks by "failing to be very presidential." Allegations that he had received support from the Unification Church headed by Rev. Sun Myung Moon hurt Kim among mainstream Christian voters, Ku said, and the ruling party hammered at statements by Kim that made him seem cavalier about national security.

The crash of a Korean Air jet, apparently caused by a bomb, also helped Roh, Ku said. The alleged terrorist act, which the government here blamed on North Korea, reminded voters of the need for continuity in the face of a perceived threat from the communist north.

Kim Dae Jung, meanwhile, never broadened his appeal beyond his home region and his constituency among some workers and students. While Roh cut into Kim Young Sam's support among the middle class, he also was able to win many working class votes away from Kim Dae Jung by reminding them that the poor are the first to suffer in a time of instability.

"Kim Dae Jung never understood that a movement and an election are different," said a pollster who accurately predicted yesterday's result. "He and his supporters were too closed within themselves, and they created a backlash against them."

Still, Kim Dae Jung's strategy may have left him in a better position to maintain power as an opposition leader, even if he comes in third, analysts said. They said Kim can continue to portray himself as the leader of the "have-nots."

Ku said Roh's final "big blow" was his "second declaration" last weekend, reminding voters of his June 29 statement and promising to continue the path of democratic reform.

Roh offered a general amnesty for political prisoners and said he would, in some unspecified way, subject his record to the people's judgment next fall, after the staging of the Olympics in Seoul.

"On the stability issue, people all along believed him," Ku said. "People really came to believe that Roh is an honest reformer, too."

The regional pattern of voting guaranteed a challenge to Roh's promise of "national reconciliation." Roh won more than 70 percent of the vote in his hometown of Taegu, while Kim Young Sam won more than 50 percent in his stronghold of Pusan, South Korea's second largest city.

Towering over both those performances, Kim Dae Jung won more than 90 percent of the vote in his home base of Kwangju.

Residents of Kim's southwest province have long felt neglected by the government, which is dominated by Taegu and Pusan natives, and their almost unanimous support for a losing cause yesterday seemed likely to fuel resentments.

The three candidates divided the Seoul vote almost evenly, with Kim Dae Jung holding a slight lead.

One key to Roh's victory was that he placed second wherever he did not place first.