With a casualness that at times was almost flippant, accused South Korean agent Tongsun Park outlined yesterday about $850,000 in payments, mostly cash, he made to members of Congress in recent years.

Many of the specifics Park acknowledged yesterday before the House Committee on Standards of Official Conduct have been disclosed piecemeal in press accounts over the past 18 months. But yesterday's hearing was the first official public accounting of park's role in what federal investigators contend was a Korean government-backed campaign to ensure continued U.S. aid.

Despite documented evidence that he reported to the Korean Central Intelligence Agency, Park continued to deny yesterday that he acted as a government agent.

"Whatever I did in this country, I did on my own," he said. He described his activities as a party-giving Washington businessman during the early 1970s as "the American success story on a small scale."

He testified that he made a bulk of his "campaign contributions" to three former House members - more than $200,000 each to Otto E. Passman (D.La.), Richard T. Hanna (D-Calif.) and Cornelius Gallagher (D-N.J.) - because they helped him retain a lucrative job as the exclusive agent for the sale of U.S. rice to Korea.

He received $9 million in commissions from 1970 to 1975 as a rice agent.

Hanna has pleaded guilty in federal court to conspiring with Park to defraud the United States. Passman was indicted last week on conspiracy and bribery charges by a federal grand jury.

They are the only former or present officials charged so far in the Justice Department investigation. The House and Senate are conducting separate internal inquiries of members' ethical conduct.

Park said the payments to Gallagher included $91,000 in cash between 1970 and 1972 and $130,000 from a "loan" that he forgave in 1975 after Gallagher had been imprisoned on an unrelated tax-evasion charge.

Park fenced with both Leon Jaworski, the committee special counsel who first led him through the list of payments, and chief counsel John Nields, who developed the details later.

The impeccably dressed Park sipped soda water during the hearing, and made several stabs at being humorous.

He complained good-naturedly at one point about the declining value of the American dollar he passed out so frequently. Another time when jaworski asked if passman got $72,000 in cash from Park in 1972, he responded that this records showed only $56,000, "but let's go with the $72,000.

During a break in the hearing, jaworski, the former Watergate special prosecutor, shook his head and said of Park's performance: "He treats this whole affair as just an ordinary sort of thing."

Some committee members and investigators said during recesses that they were not amused by Park's attitude.

Rep. Bruce F. Caputo (R.N.Y.) said, "He acted the same way in the executive (closed) session as he described hundreds of thousands of dollars in payoffs. I don't think it's funny. I think it's appalling."

Other payments Park acknowledge yesterday include:

Checks ranging from $100 to $1,000 to each of about 20 House members in 1970 and 1972.

About $31,500 in cash in then - Rep. William E. Minshall (R-Ohio) from 1970 to 1973 as well as a $20,000 or $25,000 cash donation through Minshall to President Nixon's 1972 reelection campaign.

$25,000 in cash to Edwin Edwards, a former House member who is now governor of Louisiana, in 1971 and 1972. The payments went to Edwards, his wife and his brother.

$10,000 cash to then Rep. Nick Galifianakis (D-N.C.) during his unsuccessful 1972 Senate race.

$3,500 in cash and checks for Rep. Edward Patten (D-N.J.) from 1970 through 1976, in the form of annual $500 contributions to his local county party.

Campaign contributions from foreign nationals have been prohibited only since Jan. 1, 1975.

A $1,000 cash "wedding present" to Rep. Charles Wilson (D-Calif.) in 1975. The money was originally in Korean currency, Park said, but was changed to U.S. dollars at Wilson's request.

Park said he also gave a $5,000 donation for Rep. John Breaux (D-La.) in 1972 and a total of $4,000 in cash to Rep. John J. Rooney (D-N.T.) in 1970 and 1972.

Breaux has denied receiving the money. Rooney died in 1975.

House Speaker Thomas P. (Tip) O'Neill Jr. was included in Park's recitation yesterday for having been the guest of honor at birthday parties in 1973 and 1974.

The first cost Park $2,000 and a $200 bet of hurricane lamps - a gift to O'Neill.

A "secret" report to the Korean government, dated Sept. 30, 1972, was included in two thick volumes of documents released by the committee yesterday.

It describes alleged payments of more than $1 million to scores of members of Congress and apparently was written by Steve Kim, an officer of the KCIA to whom Park reported.

Park testified that many of those payments were false and that Steve Kim was just a "good friend."

Nields' questioning yesterday focused on Park's attempts in 1971 and early 1972 to regain the rice agent's job he had lost because of complaints by government officials such as then-Ambassador Kim Dong Jo that he was hurting Korea.

Park was reluctant to mention the envoy's name though he acknowledged the ambassador had criticized him.

Committee investigators have been trying to obtain former ambassador Kim's testimony because of reports he also paid off members of Congress. The Korean government recently has shown signs that an agreement on questioning Kim in Korea might be worked out.

Park got Hanna and Gallagher to help him generate letters from 14 members of Congress to president Park Chung Hee in Mid-1971 praising his work.

In early 1972, Gallagher and Tongsun Park met in Seoul with Lee Hu Rak, then director of the KCIA, yesterday's testimony showed.

In a March 21 diary entry, park noted that he had seen Lee and added: "Riviera resolved." This was his code, he said, that meant his exclusive job as rice agent had been restored.

Park's relations with passman changed notably during this same period. In December 1971, Passman had written Philip Habib, then U.S. ambassador to Korea, complaining about Park's unethical activities.

But a month later, park played host to Passman in Seoul and Hong Kong and agreed to underwrite each of his future campaigns with at least $50,000.

Investigators estimated Park's payments to passman over the next four years at about $475,000. Park said he didn't think they were that high.

At second, at the Madison Hotel, O'Neill was given a $300 set of golf clubs. Though it wasn't mentioned at the hearing, investigators said later that park picked up a $4,000 tab for that party.

Park said he thought other members of Congress would help pay for the two O'Neill parties. "I'm still trying to collect," he said.

O'Neill's name is expected to come up again today or tomorrow when Park is asked more about some mysterious reports the committee obtained from the Justice Department late last week.