A total of 650 potential jurors will be called Tuesday when the trial of 12 Hanaif Muslims begins in D.C. Superior Court on charges of murder, kidnaping and other offenses arising from the takeover of three Washington buildings here in March.

Judge Nicholas S. Nunzio disclosed the size of the panel yesterday during a hearing at which the Hanafis made it clear that they wished to be tried together rather than separately, and at which two of the defendants said they wished to represent themselves.

The decision to remain together - despite advice from some defense attorneys that they might fare better if they were tried separately - was seen as in keeping with the loyalty the defendants have demonstrated toward Hamaas Abdul Khaalis, 54, also known as Ernest Timothy McGee. He is the alleged leader of the March sieges in which 149 persons were taken hostage and one person was killed.

The size of the jury panel compares with the panel called for the trial of five men accused of murdering seven Hanafis at the Hanafi headquarters on upper 16th Street NW in January, 1973. All seven victims were members of Khaalis' family.

The indictment in this case charges that the Hanafis, led by Khaalis, took the hostages to compel federal authorities to turn over to them the men convicted of the 1973 murders. According to statements by Khaalis, he wished to mete out his own punishment to them.

Nunzio also announced that the Hanafis would be tried in the same courtroom that was used for the trials arising from the 1973 murders. He said the courtroom, in which special security devices were installed for the murder trials, would be modified to accommodate the 12 defendants and their attorneys in this case.

Chief Judge Harold H. Greene of D.C. Superior Court asked the judges of the U.S. District Court and the U.S. Court of Appeals here for the use of a courtroom in the U.S. Courthouse for the trial.The courtrooms in the federal facility are larger than those in Superior Court, and it was felt that the trial could be conducted there more easily.

The federal judges refused this request. Chief Judge William B. Bryant of the U.S. District Court said the federal judges believed that greater security could be provided at Superior Court.

Judge Nunzio said yesterday that he hoped the process of selecting 12 jurors and 12 alternates from the 650-member panel to be called Tuesday would be completed within a week. When the jury has been selected, he said, it's members will be sequestered until the trial is over.

Assistant U.S. Attorneys Martin J. Linsky and Mark H. Tuohey III, the prosecutors, have said that they expect the trial to last from one to two months.

Among the motions on which Nunzio ruled were requests by Abdul Salaam, 31, also known as Clarence White, and Abdul Shaheed, 23, also known as Marvin Sadler, that they be allowed to represent themselves.

Nunzio said they could, but directed that Francis Smith and Charles Kubsinski, their court-appointed attorneys, remain with them to give guidance throughout the trial.

Nunzio also granted a government motion that Harry T. Alexander, a former Superior Court judge who has been retained by Khaalis as his counsel, not be addressed as "Judge" during the trial.