The Justice Department's top prosecutor told a group of freshmen members of Congress yesterday that he expects four more criminal indictments in the South Korean influence-buying investigation, hopefully by March 1.

Members of the group of Democrats who listened to Assistant Attorney General Benjamin R. Civiletti said after the closed meeting that evidence on an additional 15 to 20 present and former members will be turned over to a parallel House investigation for use in possible disciplinary proceedings.

In addition, Civiletti assured the members that his investigators were also pursuing leads of a possible cover-up by Nixon administration officials who may have been aware of the Korean lobbying effort but did nothing to stop it, the members said.

Rep. Leon Parnetta (D-Calif.), chairman of the freshman group, said yesterday tht he asked for the briefing because the junior members were concerned about reports that the Justice Department and internal House investigations were not cooperating.

Rep. Allen E. Ertel (D-Pa.), who has introduced a House Resolution calling on the Korean government to make Park and other witnesses available to the internal investigation, said, "I wanted to emphasize to him [Civiletti] that the entire House is now in a shadow and we want to get the whole truth out."

Both said they got the impression that the

Justice Department investigations would be finished when new indictments are brought. So far only former representative Richard T. Hanna (D-Cailf.) has been indicted in connection with the alleged Korean campaign to ensure continued U.S. aid to the Seoul regime.

The Justice Department investigation so far as been intent on cases of criminal conduct by individual members of Congress who took illegal favors from Korean lobbyists, but has been placing increasing emphasis lately on exeuctive branch awareness of the plan.

Panetta and Ertel said that Civiletti told the group that Justice attorneys were examining what former attorney general John N. Mitchell did with information about the alleged campaign that was available as early as 1972 from U.S. intelligence sources.

Members of Congress mentioned as having accepted money or gifts from Park said they were never warned he was a Korean agent.