The verbal skirmishing surrounding Tongsun Park's possible return to the United States escalated again yesterday as House investigators again demanded, in threatening tones, that Park tell Congress what he knows about the Korean influence-buying scandal.

Leon Jaworski, chief investigator for the House Committee on Standards of Official Conduct, said he has formally "requested that the South Korean government make Mr. Park available for testimony in proceedings of the committee."

He asked the State Department to forward the message to Seoul and secure a "prompt unequivocal response."

If that "request" is not granted, Jaworski said, the South Korean government could expect "the most severe adverse consequences" - an apparent threat that Congress might cut U.S. aid to Korea.

But a top South Korean government official in Seoul told the Associated Press that Tongsun Park "already has made it clear that he would not testify" before the congressional committees investigating the Korean scheme.

In the midst of all the talk, Justice Department investigators were packing their bags and lie detectors in preparation for their departure this morning for Seoul, where they will undertake about two weeks' interrogation of Park, a one-time Washington businessman who may know more than anyone else about the South Korean effort to buy friends and influence among senior U.S. officials.

Park has been indicted on federal charges that he conspired to bribe members of Congress as a secret agent of the South Korean government. He left Washington 15 months ago and refused numerous appeals that he return to answer questions about the Korean program.

Last week, though, Park and Korean officials reached a settlement with the Justice Department in which Park agreed, in return for immunity from prosecution, to talk to Justice investigators.

Jaworski was livid about that agreement, because it made no express provision for Park to testify before congressional probers.

The agreement did not preclude such testimony, however: under its terms, Park could be forced to appear before Congress if the committee issued a subpoena.

The House committee said Wednesday it would serve a subpoena upon Park as soon as the elusive Korean enters U.S. jurisdiction.

In yesterday's broadside, however, Jaworski offered a new proposal: he would agree not to issue a formal subpoena if Park would agree to appear voluntarily before the House committee.

Peter White, Jaworski's chief deputy, said such an agreement would enhance the chances of Park's testifying soon before the committee. It might be months or even a year, White said, before Park returns to the United States under his agreement with the Justice Department.

It was not clear from Jaworski's statement yesterday whether he is more angry at the Justice Department or the South Koreans.

He called Justice's agreement with Park "ill-advised," asserting that it undetermines the "rights and interests of the legislative branch."

"South Korea can cure this affront to Congress . . . by according Congress at least the same rights as those granted to the Justice Department," Jaworski said.

In Seoul, South Korea's foreign minister, Park Tong Jin, told reporters that Tongsun Park "has already made it clear that he would not testify at any U.S. government agency other than court."

The Justice Department team leaving for Seoul today includes three lawyers from the department's Criminal Division, three FBI agents, including a lie detector operator, and a court reporter.

Dan Swillinger, an investigator for the Senate's separate investigation of the Korean affair, will go with the Justice team. Jaworski's House investigators will not be represented on the trip.