A spokesman for the American Broadcasting Co. said yesterday that a report by its special investigator on the suspended U.S. Boxing Championships tournament will be released "momentarily."

The 300-page report by attorney Michael Armstrong, who previously investigated corruption, in the New York City police department, is expected to clear tournament promoter Don King of any wrongdoing.

Armstrong submitted an "interim" report on his investigation to the Federal Communications Commission recently and was asked for more and clarifying information in view of media reports of misrepresentation of fighters' records and eligibility standards for competing in the tournament.

Meanwhile, King announced yesterday the promotion of a lightweight title bout between champion Roberto Duran and Edwin Viruet which will be telecast by ABC from Philadelphia Feb. 17.

Before Armstrong's investigation was finished, the network had announced it was telecasting another King promotion, a heavyweight bout between Jimmy Young and Ken Norton, but at the time noted that it could withdraw if the probe affected King adversely.

The promoter has not been charged with any of the irregularities that resulted in the tournament's suspension.

A source familiar with the Federal Bureau of Investigation's role in conducting interviews for a federal grand jury in Baltimore looking into the allegations connected with the boxing tournament speculated, "I don't think anything will come out of it (such as indictments)."

Jim Spence, vice president of sports planning for ABC, was quoted as saying last month in Broadcasting magazine that "Nobody to this moment has proved Don King personally culpable of any wrongdoing."

Spence also was quoted as saying that, barring any confirmed illegalities turned up by Armstrong or the federal grand jury, the network could go back on the air with the tournament as early as January.

The House Interstate and Foreign Commerce Subcommittee on Communications also received the "interim" report from Armstrong and other information from the network.

The subcommittee plans to begin hearings next month on the relationship between the three major networks and professional and amateur sports.

Armstrong previously noted that since he no longer is part of any government agency he was not able to subpoena persons to testify in his investigation, could not compel them to be put under oath, or exercise any threat of law enforcement.

He did solicit affidavits from several figures who have charged that they were asked to make kickbacks to get into the tournament, had their boxing records misrepresented and/or their ratings rigged to make them eligible.

James A. Farley Jr., former chairman of the New York State Athletic Commission and an official of the tournament, resigned under allegations of having a conflict of interest.

Scott LeDoux, who charges after a loss to Johnny Boudreaux in a bout at the U.S. Naval Academy that the ring officials were biased in favor of boxers controlled by consultants to King, has testified before the federal grand jury.

He was later suspended by the Maryland Athletic Commission because of unsportsmanlike conduct after the bout, which he admitted.

A booking agent has been sued by a Houston boxer who particpated in the tournament and several other boxers have sued ABC, contending that the suspension of the tournament cost them anticipated further purses.