Egypt's Supreme Military Court abruptly cut short the trial of the four accused assassins of the late president Anwar Sadat today, as well as that of 20 other alleged accomplices and announced it will hand down sentences Saturday.

The decision, coming in the midst of a confrontation between the 35-man defense team and the court, seemed likely to cast doubt on the fairness of the proceedings, which have been held mostly in secret since the opening session Nov. 21.

Abdel Halim Ramadan, the chief defense counsel, and his colleagues immediately held a press conference to denounce the action. They said it had been taken after the military police barred them from entering the court this morning and summarily appointed other lawyers for the accused.

"There is a crime being committed to assassinate all these people the defendants without a legal trial," Ramadan said. He had been accused of contempt of court Monday and was appearing today before another tribunal when the military judges made their decision.

The government prosecutor has asked for the death sentence for all 24 defendants, although only four of them, led by Lt. Khalid Ahmed Shawki Islambouli, were directly involved in the attack on Sadat while he was reviewing a military parade on Oct. 6.

The others either were involved in an armed uprising in the Egyptian city of Asyut that took place a few days after the assassination or were accused of having ties with the Islambouli group.

Ramadan said the court had appointed 24 "unknown lawyers" for the last session, which he said lasted only 1 1/2 hours before the court made known its decision.

Earlier, the lawyer said in an interview that the defense had completed its brief for just 10 of the 24 accused and needed at least several more months to complete its deliberations.

The official Middle East News Agency said in a brief report that the defense had finished its presentation and that the court would hand down its verdicts on Saturday at an open session.

The confrontation between defense lawyers and the three-man military court came into the open Monday, when Ramadan entered a motion to have the trial switched to a civilian tribunal and accused the court of making errors and omitting materials from the official record of the proceedings.

When his appeal was rejected and he reportedly offended the military judges, Ramadan was accused of "insulting" the court and found in contempt. He faces a possible sentence of one year in jail or a $60 fine.

It was not immediately clear what Ramadan and the other members of the defense team planned to do. But Ramadan said at today's press conference, held on the lawn outside the Lawyers' Association building, that he and his colleagues probably would appeal the court's decision.

Since the trial began more than three months ago, the defense has been attempting to prove that Sadat was ruling in a manner contrary to Islamic law and that the four accused assassins had no other recourse than the gun to depose him.

Therefore, the defense has argued, his assassination was justifiable according to Islamic law.

In effect, the defense has tried to put the slain president on trial, questioning his behavior from his youth, when he was involved in the 1946 assassination of a pro-British government minister, until his arrest of Moslem and Christian leaders during his harsh crackdown on religious extremism a month before his assassination. "Our strategy is to prove that Sadat was a killer, a terrorist, from the time he was a youth," Ramadan said in the earlier interview. "He governed the country by terrorism."

One of the reasons the government was thought to have decided to close the trial to the press and public was precisely because of this defense strategy and the desire to prevent the country and Sadat's family from undergoing such an ordeal.

Hardly a word about the trial has appeared in the local press since the first two sessions--the only ones made public. Nor has much been published abroad about it, again because of the government decision to close the proceedings to all but the defense lawyers.

Thus, little is known about how the trial went, apart from occasional accusations and statements issued about its conduct by the defense lawyers.

At one point in late December, they all walked out of court and threatened to resign over the judges' refusal to allow them to call a number of defense witnesses, including the slain president's wife, Jehan Sadat, and President Hosni Mubarak, who was sitting next to Sadat when the assassins struck.

But they returned after the bar association interceded to find a compromise allowing the trial to resume.