Justice Department officials told a group of junior House members yesterday that the department's investigation of criminal aspects of the Korean influence-buying scandal is about 80 per cent complete, with "a very few" indictments possible by autumn.

But Benjamin Civiletti, chief of the department's Criminal Division, who joined Attorney General Griffin B. Bell in an unusual public discussion of the probe, also suggested that Justice investigators do not yet have enough evidence to bring a major indictment against Tongsun Park, who is alleged to have been the central South Korean operative in the effort to buy influence in Congress.

Although Civiletti did not say so, the lack of evidence of major crimes by Park would presumably mean a lack of evidence as well to support major charges, such as bribery or defrauding the government, against members of Congress who allegedly received favors from Park.

Even without evidence against Park, however, the department could bring indictments on charges such as income tax evasion against the members of Congress. There are indications that the department's first indictments in the case will involve such charges.

Bell had scheduled the presentation - at the urging of House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) - to soothe congressional investigation. But interviews after the hour-long session indicated that many members present were more miffed than mollified.

Representatives complained about the Justice officials' refusal to discuss specifics of the investigation and Bell's refusal to answer questions from the 100 House members who jammed a Rayburn House Office Building meeting room for the session.

Civiletti said the investigation has made "enormous progress" since he took it over in March. He said he has put 12 FBI agents and 12 Internal Revenue Service agents on the case full time to work with six prosecutors.

But he conceded that there are problems. The main one, he said, is that Park has left Washington for London, and the department can't get him back.

Civiletti said Park could not be extradited because investigators do not now have "evidence of a chargeable crime subject to the extradition treaty."

The U.S. extradition treaty with England covers bribery and defrauding the government. Thus Civiletti was intimating that Justice does not yet have a case against Park on those charges.

Other Justice officials have said that Park could be prosecuted for failing to register as a foreign agent. That crime is not covered by the extradition treaty.

In his brief remarks to the House members. Bell twice observed that the Korea matter has "cast a cloud over Congress."

O'Neill has been using the same phrase recently, but several members yesterday were visibly perturbed that an executive official would offer such an assertion.

"Clouds over Congress are none of his business," said an angry Millicent H. Fenwick (R.N.J.). "Let him enforce the law and we'll worry about our reputation."

In a related development, the Senate ethics committee has asked Central Intelligence Agency Director Stansfield Turner to brief members' behind closed doors today on what U.S. intelligence reports say about senators' involvement in the Korean affair.

Sen. Harrison H. Schmitt (R.H.M.), a member of the ethics committee, said yesterday that he had reviewed some CIA Documents with Sen. Adlai E. Stevenson (D-Ill.), the ethics committee chairman. They found nothing to indicate senators had accepted such favors, he said.