U.S. Attorney General Griffin B. Bell has told President Carter that he expects the indictment of several present and former congressmen in connection with an influence-buying scheme by South Korea on Capitol Hill, according to Justice Department sources.

Between four and six indictments are expected within the next few months, according to one of the sources.

At a Feb. 9 meeting with Bell, the President urged him to expedite the grand jury investigation of the scheme, which involved the alleged payment of between $500,000 and $1 million a year since 1970 incash and gifts to congressman to influence their position on legislation concerning South Korea.

At the Feb. 9 White House spokesman Jody Powell acknowledged yesterday.

"These investigations should be pursued as rapidly as possible consistent with being thorough and just," Powell quoted Carter as telling Bell.

However, Bell's recent public statements calling for a prompt conclusion to the investigation have created concern in some quarters of the Justice Department that such expressions of impatience with the pace of the investigation will encourage some witnesses not to cooperate. Such witnesses might anticipate the investigation would be terminated before they could be compelled to cooperate.

Sources familiar with the investigation are also worried that Bell, although briefed on the details of the probe, does not yet fully understand the unusually complicated network of alleged involvements between South Korean agents and U.S. congressmen and thus may not be willing to give the investigators the year or more they may feel they need to complete the investigation.

There is also concern that Carter and Bell, despite statements urging a through probe, are not sensitive to the appearance of political motivation in a Democratic President expediting an investigation involving more than 20 congressmen, most of whom are Democrats.

A number of congressment have acknowledged receiving cash from South Korean businessman Tongsun Park and embassy officials. The State Department has also asknowledged that a White House aide was handed an evelope in Seoul filled with $10,000 in $100 bills. The State Department returned the envelope to the Korean official who offered it.

The investigation has already included hundreds of interviews with congressmen and their aides. Several former South Korean officials are reportedly cooperating with the probe.

Last Sunday on CBS's Face the Nation, Bell said, "A lot of our institutions are under attack in this country, and there's no point of writing every day or thinking everyday about the Congress being corrupt and some large number of congressmen being involved, if they're not involved or if there's no evidence of it.

"It's the sort of thing that in a free society, you ought to be able to investigate and bring the investigation to an end. Otherwise, it festers, and it's a very bad thing in a society such as ours . . . it seems to me that you don't have to run a grand jury investigation for months or years to find out whether you've got a case or not.

". . . All I've asked is, let me know what the case is. If we don't have a case, let's say so; if we do let's indict. That's all I want to do."

Bell has set a deadline of 60 days for receiving a more detailed report on the status of the investigation.

Bell is frustrated, his associates say, by estimates that the investigation may take over a year to complete and wants assurance that it is focued on particular targets on whom sufficient information to indict has already been received.

Some Justice Department lawyers are disturbed about what they call Bell's "indict or clear" policy, in which investigations would be terminated if evidence to support an indictment is not found in early stages of the investigation.

The difficulty with the South Korean investigation, sources, say, is that some allegations linking officials and payments are supported largely by circumstantial evidence - which is considered reliable but requires independent corroboration.

Some of the circumstances evidence apparently comes from the Korean Central Intelligence Agency's No. 2 man in Washington, Kim San Keun, who has been cooperating with the investigation.

Apparently considered reliable after polygraph testing, much of Kim's testimonys based on conversations with and reports from other South Korean agents. Investigators are attempting to corroborate this and other similar testimony with eyewitness accounts and financial records.

Prosecutors are also reportedly concerned that much of their potential "conspiracy" case is based on sensitive intelligent reports about discussions in South Korea of the plot, allegedly directed by President Park Chung Hee, to create a favorable legislative climate here.

They expect those reports might be dificult to introduce at a trial and anticipate a lengthy battle with State Department and intelligence officials to get the material declassified.

Bell's energetic support will be required in any such battle, Justice observers say.

Prosecutors at present enjoy the advantage of access to intelligence cables and reports, whihc officials under investigation do not have. Justice officials say that if Bell prevails on immediate indictments, the larger group of officials under investigation will benefit when the intelligence made available in pretrial preparratins.