The National Collegiate Athletic Association has been assumed unfairly to be "a czarist regime" with autocratic powers by the congressional subcommittee that is investigating its practices, NCAA executive director Walter Byers has charged.

In a Nov. 20 letter to Rep. John E. Moss ((D-Calif), chairman of the House Sub-committee on Oversigh Byers forcefully denieid that the NCAA staff has attempted to impeded the Subcommittee's probe or "initimidate" any member institution from supplying information.

It seems to us that one of the problems in communications between us is that there are those within the Sub-committee or the staff who assume the NCAA is a Czarist regime held secure by an awesome authority which wreaks revenge upon informers. Nothing could be further from the fact." Byers wrote in his letter, of which a copy was obtained by The Washington Post.

"I unequivocally state to you," Byers went on, "that I am not aware of an attempt by any NCAA staff member to intimidate any member institution at any time and, specifically, with respect to its supplying information to your Subcommittee."

Byers was responding to a strongly worded Nov. 17 letter from Moss accusing the NCAA of "bad faith and a reckless disregard for the seriousness of this investigation."

Moses's Subcommittee is scrutiniizing the NCAA, attempting to determine whether it is violating any antitrust laws, whether its investigative methods provide for due process, and whethere the penalties assessed institutions, athletes and coaches found guilty of rules infractions are fair and equitable.

Moss's letter, which announced a Subcommittee vote to subpoena confidential case reports that the NCAA had declined to turn over voluntarily, also charged that members of the NCAA staff had made phone calls to officials of member institutions that were "perceived, rightly or wrongly, as veiled threats of reprisal."

Byers found the tone and "several of the implications" of Moss' letter surprising and disturbing.

He defended the NCAA's initial refusal to surrender files of NCAA investigations of infractions cases against some 100 schools, dating to 1970, without permission of the schools involved.

"These institutions . . . have voluntarily provided this information in cooperation with the association's enforcement program on the basis that the information will be held in confidence. We are bound by that commitment." Byers wrote.

A subpoena for the documents was served last week at NCAA headquarters in Shawnee Mission, Kan. The Subcommittee staff acknowledged receipt of seven large cardboard boxes presumably containing all the subpoenaed documents, yesterday.

"We welcome the investigation. We have nothing to hide. In fact, we are proud oif the NCAA and its accomplishments." Byers declared.

"What does puzzle us,however, is why you seek the confidential case reports of the member institutions without seeking their permission," his letter to Moss continued.

"If the NCAA has abused the authority given to it by its members, if it has violated due process, if the committee on infractions has decreed unjust penalties, then it would seem that all nenver institutions which have suffered under such tyranny would be anxious, indeed eager, to provide your Subcommittee with all possible forms of evidence to supporot such allegations, including their case files and other data they might have in their possession.

"Would not an inquiry directly to the chief executive officer of each such institution satisfy your aims and at the same time, respect the obligation we have undertaken in the administration of the NCAA enforcement program ... specifically approved by the member institutions themselves?"

Even though Moss has given assurances that the confidentiality of the subpoenaed files will not be compromised, citing "the long and unblemished record of this subcommittee in handling sensitive documents," some NCAA staff members remain fearful that the contents of the files will be made public, leading toi an embrassment of schools and private citizens that will encumber future investigations.