A federal judge in Alexandria yesterday ordered author Tad Szule to reveal the names of the sources who told him that convicted Watergate burglar E. Howard Hunt Jr. was the CIA's acting chief in Mexico City when President Kennedy's assassin, Lee Harvey Oswald, was there.

U.S. District Court Judge Orea R. Lewis ordered Szulc to give the names to Hunt's attorney. Ellis Rubin of Miami, who claims that Szulc's sources are essential to a $2 million libel suit he is pressing against another author whose book allegedly links Hunt to a Kennedy assassination plot.

Lewis, who has said on several occasions that he does not always read court papers submitted to him before hearings, ruled against Szulc because the writer did not appear in court. Lewis did not address the First Amendment privilege of protection of news sources that Szulc cited in court papers opposing Hunt's request.

Because U.S. marshals had personally notified Szulc of the hearing. Lewis said, "Let the order show (Szulc was duly served in person: he did not appear and being no opposition to the question, the court is directed that he appear before whomever - Mr. Rubin, you can set that up - and answer these questions."

Szulc's attorney William D. Rogers, said yesterday that Szule was represented in the bearing by court papers that he had filed which requested more time to fully address the First Amendment question. Rogers said he had not been notified of the hearing until about a couple days ago. We were there in terms of the [court] paper." Rogers said.

Rogers said he may ask for a rehearing on the case.

Hunt a former Central Intelligence Agency employe has denied he wa in Mexico City in 1963 and denies any connection with Kennedy's assassination. Hunt is contesting statements in a book by Alan J. Weberman. "Coup d'Etat in America, the CIA and the Assassination of John F. Kennedy," which Hunt said libeled him by linking him to an assassination plot.

Hunt contends that the statements in Weberman's book placing him in Mexico City when Oswald was there were taken from Szulc's book. "Compulsive Spy: The Strange Career of E. Howard Hunt."

During a June deposition Szulc, a former New York Times reporter and now a free-lance writer refused to say who told him that Hunt was in Mexico City. Szulc refused to answer, citing "the professional confidentiality of sources" and "journalistic privilege."