American and South Korean prosecutors begin negotiating Monday over access to accused South Korean agent Tongsun Park in an atmosphere where the symbolic outcome of the talks may be as important as their practical effect.

Both sides have been careful not to raise expectations of a breakthrough in the impasse over the Justice Department's request to have Park returned to the United States. The onetime Washington playboy faces a 36-count felony indistment in connection with alleged South Korean influence-buying on Capitol Hill in the early 1970s. His testimony is considered crucial to the success of the continuing Justice Department investigation.

Park flew to Seoul from London shortly before the indictment was handed down in August. The South Korean government consistently has denied any connection with Tongsun Park and so far has refused to help get him back. There is no extradition treaty between the two countries.

Benjamin R. Civiletti, head of the Justice Department's Criminal Division, has said he does not expect to question Tongsun Park during his visit to Seoul this week, but it is clear that the Justice Department down expect some sign of South Korean cooperation to result from the talks. A continuing lack of progress would be a signal to members of Congress to try again to cut off U.S. aid to South Korea. Such an effort in the House last month failed by only about 25 votes.

The South Korean government, on the other hand, also has symbols to consider and is unlikely to do anything that would give any appearance of bowing to American pressure.

The country, which once depended greatly on U.S. aid, is now proud of it economic progress. Side effects of that boom were evident here this weekend as a pair of international trade conferences and a swarm of Japanese tourists overflowed the luxury hotels.

The anticipation surrounding Civiletti's visit has been sharpened by the indictment Friday of former Rep. Richard T. Hanna (D-Calif.), the first alleged lobbying scheme, and by this week's scheduled public hearings by a House committee conducting a parallel investigation.

Both events will focus additional public attention on allegations of South Korean government involvement. The Hanna indictment, for example, mentions correspondence from Hanna to four directors of the Korean Central Intelligence Agency and to President Park Chung Hee. It also names two KCIA directors as well as Tongsun Park as "unindicted co-conspirators."

The House committee is expected to call several witnesses, including former top KCIA officials, to testify about the alleged scheme. In fact, Leon Jaworski, the former Watergate special prosecutor who is the committee's special counsel, is known to view one benefit of the open hearings as increased public pressure on the South Koreans to cooperate in the investigations.

Civiletti said in an interview just before arriving in Seoul yesterday that the Hanna indictment was not timed as part of a strategy to put more pressure on the Soth Korean government.

He said the indictment was delayed about a week so the House commettee could approve letting Justice Department attorneys review Hanna's sworn statements to Jaworski's investigators. Hanna refused to answer questions before a federal grand jury.

Civiletti's awareness of the sensitivity of the negotiations to the South Koreans was evident in the carefully worded statement he released after conferring with embassy officials on arrivals yesterday. He pointed out that his department was responsible for investigating and prosecuting American, not South Korean officials.

In the earlier interview, he stressed that the Justice Department had not abandoned its requests, through President Carter and the State Department, that Park be returned. He did not rule out some compromise, however, such as interviewing Park in a third country under the condition that his testimony could be used on a trial.

Joining Civiletti in the talks will be Paul Michel, the Justice Department attorney heading the South Korean investigation, and Allan Meyer, the FBI's chief investigator in the case.