FBI Director Clarence M. Kelley has suspended an FBI agent in Washington for three weeks without pay and given him a disciplinary transfer alter learning that the agent allegedly is living with a woman out of wedlock.

Kelley sent a personal letter to the agent, Jack T. Colwell, saying that he was suspended because "you engaged in indiscretions which reflect unfavorably on your moral character and which are not in keeping with the high standards expected of employees of the FBI. This conduct on your part is inexcusable and will not be tolerated by me."

Colwell included Kelley's letter as part of the suit he filed yesterday in U.S. District Court in Alexandria against the FBI, Kelley and three supervisors.He is seeking back pay for the suspension period, deletion of any mention of the dispute from his personnel record and permission to stay in the FBI's Washington field office.

Kelley told Colwell in a second letter that he was transferring him to the FBI's New York office, effective Nov. 1. Cowell's attorney. Stephen Pickard, said that he and Colwell feel that the tranfser is the result of his allegedly living with the woman out of wedlock and "is what they've done to fire him in effect. We feel this is what they do to get rid of you." Pickard said the second Kelley letter "is known in the FBI as a disciplinary transfer."

Colwell was suspended from Sept. 29 through Oct. 20. "Henceforth you are to conduct yourself in such a manner as to be above reproach so that criticism of this nature will not again be necessary." Kelley said in the personal letter to Colwell.

An FBI spokesman said yesterday the bureau could not comment on the case because it is in litigation.

Nick F. Stames, the special agent-in-charge charge of the FBI Washington field office, who is named as one of the defendants in the suit, said in a telephone interview, "I don't see that thaf's a matter for The Washington Post, an internal situation."

When asked about Colwell's allegations, Stames said, "I'm not going to add to your story."

Colwell, an agent since May 7, 1973, alleged in his suit than on Sept. 17 he was called into a meeting with FBI administrative assistant Joseph P. Shultie Jr. and Erle L. Norton Jr., an FBI application supervisor. At the meeting "several accusations of alleged immoral conduct were made against (Colwell) including that he was living with a woman not his wife [WORD ILLEGIBLE] Colwell's suit alleges.

Pickard said Colwell is separated from his wife, but is not divorced.

On Sept. 15 Colwell said Shultie and Norton told him to either leave his house in Chantilly, which he bought last year, or have his friend leave, the suit alleges. Pickard would neither confirm nor deny the allegation that Colwell is living with a woman out of wedlock.

On Sept. 29, Colwell received the letter from Kelley and a notice of the transfer, the suit alleged.

Coldwell appealed the decision to Kelley on Oct. 7, but his appeal was denied, the suit states.

Stames said that the FBI follows a code of conduct for all Justice Department employees.

The code specifically covers conflict of interest, fiancial disclosure, improper use of entertainment, and other forms of conduct such as a ban on accepting free gifts and entertainment.

One section, titled "Conduct Prejudicial to the Government," states that "no employee shall engage in criminal, infamous, dishonest, immoral or nortoriously disgraceful conduct or other conduct prejudicial to the government."

Another portion of the code states that "any person in government service should: put loyalty to the highest moral principles and to the country above loyalty to persons, party or government department."

There is no specific section on improper sexual conduct.

Colwell claimed in his suit that his "conduct is neither immoral under current standards nor disrespective of the high standard of conduct expected by the FBI . . ."