As the largest trial in recent Egyptian history opened today, 300 Moslem fundamentalists charged with attempting to overthrow the government following Anwar Sadat's assassination last year threatened that their followers will avenge their trial.

Former Lt. Col. Aboud Zomor, 28, leader of the group that carried out a series of bloody operations in Upper Egypt after the president's killing in October last year, said before the trial opened: "We, the youth of the Islamic Jamaat groupings , are charged with trying to overthrow the ruling system and establishing an Islamic state. This is an honor for us."

Having admitted the charge, Zomor recommended that the president follow the rules of Islamic sharia, or religious law. "Repent and follow God's path," his voice echoed in the spacious courtroom constructed especially for this trial at the fairgrounds in a Cairo suburb. He accused President Hosni Mubarak of issuing instructions for torturing approximately 10,000 persons suspected of belonging to other groups hostile to the secular government.

Zomor, sentenced to life imprisonment at hard labor for his role in the assassination and facing the possibility of a death sentence if found guilty in this trial, said, "I am yearning to join Khaled Islambouli and his brothers in heaven," referring to Sadat's killers. He described them as "the most pious five martyrs of Islam in this century." Sadat's assassins were executed last spring.

The bearded youngsters jammed in 12 cages chanted "Moslem blood is no offering for the Americans and the Jews," and threatened: "Mubarak, you will not escape the vengeance of Islam."