Tongsun Park was caught giving evasive and incomplete answers yesterday, House members said, as congressional investigators began asking him specific questions about his involvement in the alleged Korean influence-buying effort on Capitol Hill.

Members of the House Committee on Standards of Official Conduct who sat in on the closed-door interrogation said the Korean businessman's responses to tough questioning from committee investigators raised considerable doubt about the credibility of his testimony on the scheme.

The questioning focused yesterday as it did in the opening session Tuesday, on trying to get Park to admit that he was an agent for the Korean government when he made hundreds of thousands of dollars in payments to members of Congress, committee members said.

The committee wants to establish if Park was acting as a foreign agent rather than a private businessman because it is illegal for members of Congress to accept cash or gifts from representatives of foreign governments.

It wasn't until late yesterday that the questioning turned to the names of members Park claims to have made payments to, one source said.

"I don't think any of us is believing him," said one Republican on the committee, who asked not to be identified. The sentiment was endorsed by four other members.

But Rep. Floyd Spence (S.C.), the committee's senior Republican, cautioned that it was too early to draw conclusions about Park's credibility. "A few more days will tell" whether the Korean's testimony can be trusted, Spence said.

Yesterday was the second day that Park, a prominent Washington socialite in the early 1970s, underwent questioning about his role in a South Korean government effort to win friends in the U.S. government.

In preparation for Park's testimony, which the committee has been trying to arrange for months, the investigators gathered voluminous information about him, including his bank and business records and testimony from his former business associates and friends.

Yesterday, committee members said, special counsel Leon Jaworski and chief counsel John Nields caught Park in answers that conflicted with the documentary evidence, or with the earlier testimony.

Rep. Bruce Caputo (R-N.Y.) said such conflicts came up "regularly" during yesterday's four hours of interrogation. Spence said they occurred "sometimes."

In any case, Caputo said, the meticulous use of documentary evidence to challenge Park's answers permitted the committee to elicit more information than had been obtained last month when Justice Department investigators questioned Park in Seoul.

Park, talking to reporters during a break in the questioning, said he thought the committee believed his testimony. "The questions were very tough," he said, but in public, at least he still displayed the cheerful self-assurance he has shown since he was first linked to the scheme two years ago.

Park could be in trouble if the committee decides his testimony is not reliable. He has been promised immunity from prosecution under a 36-count federal indictment charging him with bribery and conspiracy in the Korean scheme. But that promise is conditional on truthful testimony before congressional and Justice Department investigators.

Members of the House committee were reticent to discuss the substance of Park's testimony, but they said he had not provided any major new evidence of wrongdoing by American officials. Asked to characterize his testimony, Park said, "There were no surprises so far."

Park has regularly said he was acting as a private individual when he contacted and entertained U.S. officials. But earlier testimony before the House committee suggested he was working with the Korean Central Intelligence Agency.

The New York Times reported yesterday that Park told the Justice Department that his contacts with the Korean CIA were strictly business deals.

The newspaper said portions of the transcript of Park's interrogation last month in Seoul show that he said he used the KCIA to help him gain a lucrative position as the sole broker for American rice sales in South Korea. According to The Times' account, Park said the KCIA had asked him to make friends with designated members of Congress, but he did not do so.

The House committee's questioning of Park will resume today and continue daily through next week.