On Feb. 7, 1975, a bus chartered by the Chile Solidarity Committee of New York left for a conference near Chicago with 19 passengers aboard.

One of them was a spy for the International Telephone & Telegraph Corp.

An ITT photographer secretly took pictures of a number of the travelers as they boarded the bus. The spy then accompanied the group to the two-day meeting, which ITT's "manager of major investigations" later summed up as "a radical summit conference with a central theme of fascist oppression, crimes and atrocities in Chile as an object lesson for the United States."

This glimmer of corporate spying on domestic political groups came to light yesterday as the result of a lawsuit against the Chicago Police Department over the activities of its so-called "Red Squad."

The suit, filed six years ago, has yet to come to trial. The "Red Squad" has been disbanded. But lawyers pressing the case have been poring over the 300,000 pages of records the squad left behind as a part of the protracted pretrial discovery process.

The ITT papers turned up in a manila envelope. The raw reports, it seems, had been shared by an ITT official with an FBI agent in New York. He, in turn, loaned them to an FBI man in Chicago who evidently turned them over to the "Red Squad." By coincidence, that unit's files were impounded by court order the following month in the midst of a full-blown furor over the unit's operations.

The Chicago lawyer who discovered the documents, Richard Gutman, said yesterday that they "demonstrate that it is not only government agencies which spy upon their critics.Political snooping is also carried out by large corporations. These private corporations, however, unlike the government agencies, are not accountable for their actions to the public."

The ITT records in question consist of 11 photographs taken as the chartered bus was about to leave New York, a two-page report identifying those in the photos and labeling the owner of the bus line as "friendly with the New York Csc [Chile Solidarity Committee] leadership." and an eight-page report on the two-day "Conference in Solidarity with Chile" that was held at Concordia College in River Forest, Ill.

The reports, according to a cover note jotted down by the New York FBI agent, were written by Jon Rogeberg -- then ITT's "manager of major investigations" and now chief investigator for the giant multinational corporation -- on the basis of information supplied to him by a source who had infiltrated the New York-based Chile committee.

At the meeting in River Forest, the conferees decided, among other things, to try to organize a protest campaign against various U.S. banks and multinational corporations, including Itt, that were doing business with the Chilean junta of Gen. Augusto Pinochet. But they agreed to assign top priority to the major auto companies that were planning to open auto assembly plants in Chile, and only second priority to companies such as ITT that already had extensive investments there.

Some of the participants were described in Rogeberg's main report in meticulous detail, including their heights, weights, and occasionally, their hairstyles, birthdates, addresses and telephone numbers. Two individuals, their names deleted as the result of court-imposed guidelines, were described as "part of the Weathermen support apparatus."

The reports were provided to FBI agent James Vermeersch, who had been stationed in New York with a special FBI squad assembled in 1970 to track down Weather Underground fugitives. Vermeersch testified here last month at the trial of two former high-ranking FBI officials that he took part in 15 to 20 surreptitious entries -- or "blackbag jobs" -- in a search for clues.

Vermeersch said that his squad concentrated on people it believed were connected to the fugitives in some way or other but who were, "in fact, living as normal citizens above ground."

In a statement issued yesterday afternoon, ITT asserted that it "has never maintained a program of political spying and infiltration." The company added, however, that "from early 1972 to the present" its facilities and personnel have been the subject of "more than 90 terrorist threats, bombings and attacks, "including a 1973 explosion at ITT world headquarters in New York and a 1974 storming of its annual stockholders' meeting in Seattle.

"The company cooperated with law enforcement agencies investigating such crimes in an attempt to protect its personnel and property from further terrorist activities," the statement said. "ITT also followed, through available sources of information, the activities of groups seeking to organize a boycott as a protest against the corporation."

Asked whether "available sources of information" included the assignment of infiltrators, ITT spokesman Steve Erenburg said that "no officer or director of ITT authorized any infiltration of a domestic organization." He said the information that turned up in Chicago was "obtained by an ITT employee . . . from a source known only to him." Erenburg also asserted that the Rogeberg reports and photographs could not be found in the company's files.

In Chicago, attorney Gutman protested that detecting crimes "is the responsibility of the appropriate law enforcement agencies, not ITT." He charged that ITT's surveillance could have had only one purpose: the disruption of law-abiding political action groups.

John H. Coatsworth of the Chicago Committee to Save Lives in Chile, one of the groups involved in the 1975 conference, added that more than "mere observation" may have taken place. He said participants at the conference also "complained of missing notes and notebooks," and at one point "the local police were summoned to the scene on the basis of anonymous and unfounded rumors."

"None of the organizations victimized by ITT spying has ever discussed, planned or engaged in any activities that could even remotely cause ITT to fear for the security of its property or the safety of its employees," Coatsworth said. He maintained that ITT was trying to disrupt efforts "to aid the victims of a bloody dictatorship" that the company "helped to install" in the first place.