PUSAN, SOUTH KOREA, OCT. 17 -- Opposition leader Kim Young Sam, kicking off his presidential campaign before a vast hometown crowd, today accused the South Korean regime of deceit and corruption and said that only he can bring democracy to South Korea.

Holding his first election rally since a military coup prematurely ended his last campaign in 1980, Kim attracted hundreds of thousands of the committed and the curious to a field by Suyong Bay here in South Korea's second-largest city. A 67-year-old farmer, who traveled several hours from his village to herald the arrival of democracy, said he was a longtime supporter of Kim but had not attended any rallies "in long, long years."

Kim's claim that attendance exceeded 2 million appeared exaggerated. The police pegged the crowd at more than half a million, and the normally progovernment Korea Herald estimated it at more than 1 million.

It was a big enough crowd, in any case, to send a message to Kim's rival opposition leader, Kim Dae Jung, that he, too, has popular support, although the rally lacked the passion of those staged by the charismatic Kim Dae Jung. The two Kims have insisted that the opposition should field only one candidate in the December election, but each has insisted that he is the rightful standard-bearer.

The rally also demonstrated that South Korea's first contested election in 16 years will be an emotional one. Kim Young Sam portrayed the choice between himself and ruling party candidate Roh Tae Woo as a choice between democracy and military rule, and he invoked rumors of corruption high in the present regime.

"I won't lie like Park Chung Hee and Chun Doo Hwan," he said, referring to the previous and present rulers, both former generals who took power in coups. "I will wipe out corruption, even if my own family or aides are involved in wrongdoing."

President Chun reluctantly agreed on July 1 to allow direct presidential elections after students and others staged determined street protests throughout June. Chun has promised to step down Feb. 25 in what would be South Korea's first peaceful transition of power.

Although the new constitution sanctioning the election will not become official until voters approve it in an Oct. 27 referendum, four major candidates this weekend intensified their campaigns to succeed Chun. Besides the two opposition Kims and Roh Tae Woo, Kim Jong Pil, a prime minister who served in the Park government in the 1960s and '70s, also is running.

Kim Jong Pil and Kim Dae Jung held indoor meetings with supporters today, while Roh traveled to Taejon to address a rally of 20,000 youth volunteers. Government-controlled MBC-TV gave more prominent coverage to Roh's small rally than to Kim Young Sam's large one.

Kim told his supporters here that the bias of government television news and the government's widespread gift-giving during a recent holiday season prove that it is "planning an unfair election."

"Now the government party is spending money like water to buy votes," he said. "Where did that money come from? From your pockets."

Kim spent most of the afternoon attacking the government and Roh, a former general and close ally of President Chun. But the rally was intended equally as a message to Kim Dae Jung, who yesterday made definite his intention to run.

"That's right, we beat the hell out of Kim Dae Jung," one aide to Kim Young Sam said as Kim's open-car motorcade came within sight of the huge crowd by Suyong Bay.

Kim Dae Jung had staged a similar homecoming rally in Kwangju last month, also attracting hundreds of thousands. Both camps hope that by demonstrating their popularity with huge rallies -- in a nation where voter preference polls are banned -- they can pressure the other side to drop out, thereby avoiding a split of the opposition vote.

"If both run, we have no chance of beating Roh," said a religious leader.

Many in the good-natured crowd today were attracted to Kim Young Sam, but not fervently committed. Others acknowledged that Kim did not make a fiery or inspiring speech, but many said they found merit in Kim's contention that his steadiness is a virtue in a time of transition.

"He is a reasonable man, with orderly priorities and common sense," said Kim Doo Hwan, 30, a worker at the Korean Seaman's Mission. "I think that is what we need right now."