Doors closed to murder trial in Egypt's 'national interest'

''I am guilty in the murder of Sadat and I admit it,'' Khalid Ahmad Shawki Istanbouli declared defiantly at the opening this week of the trial of the accused assassins of the late Anwar Sadat.

''That we killed the others deliberately we deny. He (Defense Minister Abu Ghazzala) was in front of me and I didn't shoot him. . . . I told him, 'Get away , you're not involved. I want this dog, this tyrant.' ''

Despite this testimony, all 24 defendants in the trial, including Istanbouli, pleaded not guilty to the charges brought against them by the state.

The team of defense lawyers sought unsuccessfully to broaden the scope of the trial to include a debate on the religious justifications for the assassination, and a critical evaluation of some of Mr. Sadat's major political acts while in office.

''I want to say that though what you say happened happened,'' said the lawyer of one of the assassins, ''there were conditions in the country that made it happen.''

''It is an issue of Islamic thought,'' said another, who along with other lawyers invited Egypt's major religious authorities to debate jailed fundamentalists on the religious principles that guided the 24 defendants accused of involvement in the assassination.

A lawyer invited two former ministers, Ismail Fahmi and Muhammad Ibrahim Kamel, both of whom resigned in protest ofMr. Sadat's pursuance of the Camp David accords, to come and testify before the court. He also invited several of the 31 political opposition figures Mr. Mubarak recently released to testify to conditions in the country shortly before the assassination.

''Every issue is around the main thought,'' said one of the lawyers. ''We, by this debate and dialogue, will find a solution to the issue of the thought of the accused.''

The prospect of these public debates on Islam's role in the state, on the virtues and vices of Sadat's 11-year rule, were quickly forestalled by the military judges. The judges rejected the requests of the defense and closed the trial to the public (when it resumes Dec. 5) for ''security'' reasons and ''the national interest.''

The court's hesitation was no doubt due to the fear that, with the current mood of the country, the debate could turn either way. It might conceivably, as the defense lawyers suggested, clear the air, and permanently discredit the violent manifestoes and self-styled moral rulings of the small semiautonomous Islamic groups scattered throughout the country.

Or, it could prove to be a Pandora's box, dividing the country between those who support the state-controlled religious establishment, and those who sympathize with independent worshippers.