U.S. District Court Judge John J. Sirica indicated yesterday he may appoint a court official to read Central Intelligence Agency documents on the assassination of John F. Kennedy that the agency is trying to keep secret.

The Judge made the suggestion after lawyer Bernard F. Fensterwald argued that he had been denied much of the material on the assassination that he had requested under the Freedom of Information Act.

Fensterwald has sued the CIA for all its information on five persons, including Lee Harvey Oswald, the man the Warren Commission said shot Kennedy. Jack Ruby, who in turn killed Oswald, also is one of the five.

Fensterwald has asked for papers on the CIA's investigation of David Ferrie, an airplane pilot who was a chief suspect in an investigation of the Kennedy death conducted in New Orleans, Perrie is dead.

He also asked for the CIA's files on Sylvia duran, a Mexican Communist and the only person to testify that Oswald had been in Mexico just before the Nov. 22, 1963 assassination.

Sylvia Odio, a Cuban woman who said that tww Cubans and Oswald met with her in Dallas just before the murder, is the fifth figure in Fensterwald's request.

Fensterwald complained that, since he made his request for the files on April 3, 1975, he has received about 25 per cent of the records and another 25 per cent have not been supplied. He told Sirica the remaining 50 per cent are so badly distorted by deletions to be worthless.

He asked the judge to look at the papers himself in private to determine the validity of the agency's claim that national security prevents disclosure.

Sirica indicated he might appoint a special master to review the documents. A special master is usually a private attorney appointed by the court to carry out a specific assignment.