SEOUL -- In the early fall, Moon Hee Sang's noodle company stopped receiving shipments of key ingredients. As a result, Moon says that late last month, he was forced to close his firm, Samjung Food Co., laying off its 120 workers. To make matters worse, he just received notice from tax authorities that he owes 100 million won -- about $125,000 -- in back taxes.

Moon describes his plight as much more than a hard-luck business failure.

He joined the political campaign of opposition leader Kim Dae Jung over the summer, and Moon now charges that his financial problems are due to illegal government pressure aimed at punishing businessmen who, like himself, oppose the ruling party's presidential candidate, Roh Tae Woo.

"Government officials told me that if I halted my relationship with Kim Dae Jung, there would be no more problems," he said in a recent interview. But Moon continued helping Kim, formally joining the campaign as a top official in charge of mobilizing the youth vote, and his firm went under. "It's a dirty trick," Moon said. "The government argues that it wants democratization, but then it does this kind of thing."

Although his account could not be independently verified, it follows the general lines of what South Korean politicians and western diplomats say is a two-pronged government campaign to scare financial supporters away from the opposition -- and into the arms of the ruling Democratic Justice Party. While there are also charges that opposition campaign officials have threatened retribution if a potential donor refuses to pitch in, most reports of donor abuse have been associated with the ruling party.

"The government is in fact intimidating people from {financially} supporting opposition candidates," said a western diplomat. Among other instruments of intimidation, he cited tax audits of businesses or business executives who give money to the main opposition candidates. He also said the head of South Korea's intelligence agency was formerly in charge of the country's tax agency.

The ruling party has denied the charges of exerting illegal pressure. It says the allegations are part of an opposition campaign to smear Roh, suggesting that the opposition's money problems stem from a lack of public support rather than from intimidation from official circles.

With the election campaign heating up as the Dec. 16 vote draws closer, the opposition is charging that the ruling party is employing a wide range of illegal election tactics, including bribing local officials, publishing slanderous pamphlets and using the broadcast media as a propaganda tool. But because of the key role of money in the campaign, the charge of illegal pressure against Korean businessmen is emerging as a crucial issue.

The scale of abuse is difficult to assess, and so is its impact.

The allegations of harassment can sometimes verge on the absurd. Local newspapers reported last week that a female election adviser to the ruling party was arrested after making violent threats to a businessman she tried to recruit in a bar in Seoul. The reports said the woman "rampaged" through the bar, shouting, "Are you supporting the opposition camps?"

While the ruling party appears to be well-funded, the three main opposition candidates are running into differing degrees of money trouble. Left-leaning Kim Dae Jung and conservative Kim Jong Pil are the worst hit. They have run advertisements in newspapers appealing for emergency donations from supporters. Kim Young Sam, considered more of a centrist, is said to be in better shape, mainly because his home region and primary source of funding is the wealthy port city of Pusan.

The candidates are legally limited to approximately $17 million in campaign expenditures, but they are all expected to go over that level. One western diplomat, asked whether the candidates together might be spending a total of $250 million, laughed and replied, "That figure may be low." The total campaign spending may be so large that some officials in Seoul fear it could spark inflation.

The cases of intimidation are hard to pin down because many of the business executives subjected to the pressure are reluctant to complain publicly. They fear even more retribution. Local newspaper reports say that some business executives have left the country temporarily or retreated into the provinces to avoid the pressure.

For example, a political source said a large company in Seoul linked to Kim Jong Pil, the conservative candidate, was being audited by tax authorities because of government suspicions that the firm was donating to Kim's campaign. Officials at the company refused requests to be interviewed about the alleged audit and insisted, through the source, that the firm's name not be mentioned.

"It's a very delicate political problem for our company," a spokesman at the firm said.

Moon, of the Samjung Noodle Co., is something of an exception. With his business closed and his involvement with Kim Dae Jung out in the open, he has little to lose, financially or politically.

In fact, Moon, 42, says he has lost more than his own holdings: a book clearinghouse run by his wife and father also faces shipment problems, he said. Most serious, though, Moon said his wife has been hospitalized from nervous exhaustion caused by the business woes.

"Everybody in the family is experiencing horrible times," he said.