As the Iran-contra hearings enter their final month and attention focuses on the role of White House and Cabinet players, it is becoming unlikely that Michael A. Ledeen, a key figure in the 1985 U.S. approach to Iran, will testify in public.

Ledeen, a National Security Council consultant at the time, has said he is eager to testify because of allegations that he profited from the arms sales he helped arrange through Israeli officials.

A scheduled appearance by Ledeen was postponed, however, although his name continues to surface in the hearings and is likely to do so again this week with the long-awaited testimony of Marine Lt. Col. Oliver L. North.

North's former secretary, Fawn Hall, and Noel Koch, a former Pentagon official, have testified that Ledeen's main function as a consultant on terrorism seemed to be to visit NSC and Pentagon offices and read classified reports on terrorism.

Hall testified, "I think that Mr. Ledeen mostly came to the office to read . . . the phone calls that came in, basically, were to say, 'Hey, I'm going to stop by today and read.' " She said he read daily and monthly Defense Intelligence Agency reports on terrorism as well as reports on how the United States had responded to various terrorist incidents.

Koch said he did not consider Ledeen to be an expert on terrorism and stopped using him as a Pentagon consultant. "There was a period in which, for reasons that I thought were good and sufficient, I stopped letting him read our -- the classified, as a consultant, and immediately I stopped -- he stopped coming around," Koch said.

In a phone interview last week Koch would not elaborate on what he meant by "good and sufficient" reasons because "this may become the subject of a separate investigation." He declined to be more specific.

But sources familiar with the investigations said that Koch has told both the congressional committees, in a sworn deposition, and investigators for independent counsel Lawrence E. Walsh that one of the reasons he became concerned was that Ledeen started asking for classified debriefing reports of a Libyan defector.

Ledeen said through his attorney, R. James Woolsey, that he did not recall asking Koch about any such defector reports. Woolsey said his client considered reduction in his Pentagon clearance to "secret" in early 1985 as a "routine administrative matter" because he had a clearance of "top secret and more" for his NSC work.

Ledeen described his consulting duties, Woolsey said, as making suggestions and sometimes writing Pentagon reports on terrorism and "talking to foreign experts, including some government officials" for the NSC.

Ledeen has listed himself as an expert on terrorism while a fellow at the Georgetown University Center for Strategic and International Studies. He served as a special assistant to then-Secretary of State Alexander M. Haig Jr. in 1981 and 1982, and later as a consultant, but not on terrorism, according to officials who dealt with the issue.

He was hired as a consultant to the Pentagon in 1983 and to the NSC by the national security adviser Robert C. McFarlane in late 1984. It was while a consultant to McFarlane and North in early 1985 that he traveled to Israel to ask then-Prime Minister Shimon Peres about intelligence on Iran.

For the rest of the year he played a key role in setting up a relationship between the U.S. government and Iranian intermediary Manucher Ghorbanifar.

Koch testified last week that North told him Ledeen negotiated the wrong price for a shipment of U.S.-made antitank missiles from Israel to Iran. "He had screwed it up," was how North described Ledeen's actions, Koch testified.

Ledeen told National Public Radio last week that he had nothing to do with negotiating missile prices and that Koch "didn't know what he was talking about."