A federal jury in Manhattan today ended the longest terrorism trial in U.S. history by convicting all 10 defendants, including Egyptian Sheik Omar Abdel Rahman, of plotting bombings and other acts of terror that were designed to intimidate the United States into changing its Middle East policies.

Some of the defendants, part of a Muslim terrorist cell that U.S. authorities began watching in the late 1980s, were arrested in 1993 as they concocted a brew of chemicals in a Queens garage. In conversations taped by the FBI, the group had discussed killing Egyptian President Hosni Mubarak and blowing up New York City landmarks to force the United States to stop supporting Egypt and Israel. The government alleged that the targets of their planned day-long bombing rampage included the United Nations headquarters, the federal building housing the FBI and the three major transportation links between Manhattan and New Jersey -- the Lincoln and Holland tunnels and the George Washington Bridge. They also talked of kidnapping former president Richard M. Nixon.

The trial, in which the group faced charges of "seditious conspiracy" and various other crimes, lasted nearly nine months and featured 200 witnesses and hundreds of exhibits. Relying heavily on the testimony of a paid FBI informant, a shadowy Egyptian ex-intelligence officer named Emad Salem, the prosecution painted a picture of a band of young Muslim radicals bent on paralyzing New York City.

The six men and six women on the jury deliberated for seven days and agreed with the prosecution on virtually every charge, finding the men guilty of 25 separate counts of conspiracy and charges related to the attempted bombings.

Eight of the 10 face a maximum of 25 to 30 years in prison without parole. Sentencing is scheduled for January.

Abdel Rahman, the blind cleric the prosecution claimed was the mastermind behind the plot, was also found guilty of plotting to kill Mubarak and faces life imprisonment.

Also facing life is El Sayyid Nosair, who was convicted for the 1990 "murder in aid of racketeering" of Rabbi Meir Kahane, leader of the Jewish Defense League. Nosair was acquitted of murder charges in state court in 1991, but convicted of related weapons charges. The jurors today agreed with prosecutors that the Kahane murder was the beginning of a series of militant acts by the Muslim cell that was encouraged by Abdel Rahman, the group's spiritual leader.

One such act was the Feb. 26, 1993, World Trade Center bombing, which killed six people, injured more than 1,000 and did $500 million worth of damage. Four people were convicted last year and sentenced to a total of 240 years in prison.

After the verdicts were read and the 10 men were being led in handcuffs from the courtroom, one of them cried out, in Arabic, "God is great." Later, on the steps of the courthouse, Lynn Stewart, attorney for Abdel Rahman, called the verdict a victory for fear and prejudice.

"The message here is put a Muslim on trial and they'll convict him," she said. "This became a trial of nationalism -- the jury acted as Americans first."

"This really is a sad day for the American justice system," said Valerie Amsterdam, an attorney for another of the defendants. "I don't feel this case was decided on the facts, on the evidence. It was decided on fear."

At the Abu Bakr mosque in Brooklyn, where the sheik once preached, the mood was subdued, sad and angry, the Associated Press reported. "This is absolutely discrimination," said Nasser Ahmed, treasurer and acting spokesman.

But Mary Jo White, U.S. attorney for the Southern District of New York, retorted that "this trial is about crimes, very serious crimes, not about religious beliefs, or ethnicity or people from any particular part of the world. Indeed, this crime is most offensive to those vast numbers of Muslims who speak and live enlightenment and peacefulness in their religion and positively contribute so much."

FBI Director Louis J. Freeh called the verdicts "an extraordinary victory in the fight against terrorism. . . . The verdicts signify our nation's resolve to resist terrorists to the limits of our abilities and authorities." The first arrests in the bombing conspiracy came in June 1993, when FBI agents took into custody five men mixing a batch of bomb explosives in a garage in Queens. The FBI had been following the group for months. With the aid of Salem, a paid FBI informant who had managed to pass himself off as a terrorist, they had recorded hundreds of hours of videotapes and audiotapes of the defendants planning their bombing spree. In the following weeks, the FBI arrested several other young Muslims and revealed what appeared to be the most ambitious terrorist conspiracy ever planned on American soil.

The tapes made by Salem had a key role in the trial. In one exchange, for example, Salem and Abdel Rahman discussed the plan to bomb the United Nations and the FBI headquarters. According to the transcripts, Abdel Rahman advises against bombing those buildings, instead recommending that Salem "find a plan to inflict damage on the American army."

But a videotape secretly taken by the FBI of the interior of the Queens garage that served as the group's informal headquarters shows several of the defendants huddling around a large cauldron, mixing what the prosecution called a "witch's brew" of explosives, while another of the defendants prayed in the corner.

"If terrorism is theater," said James Kallstrom, head of the FBI's New York City office, "Then these acts of terrorism planned by these men were theater of the absurd."

During the trial, the defense argued that Salem was an unreliable witness. He admitted to lying in the past and bragging about his exploits. A number of the defendants also accused Salem of entrapment. They said they had been duped into joining the plot because Salem had told them that he was training them to fight with Muslims in Bosnia.

"They baited these guys with Bosnia and halfway through, they switched to talking about American targets," attorney Amsterdam said during the trial.

Attorneys for Abdel Rahman, meanwhile, contended that he had merely talked in a controversial way about the responsibility of Muslims to "fight the enemies of God." In one tape of an Abdel Rahman speech introduced by the prosecution, for example, he told his followers that they should be proud to be terrorists.

"You shouldn't punish the sheik for his outspoken ideas," Stewart told the jury, during the trial's closing arguments. "That's what America is all about, isn't it?"

But the jury rejected each of these arguments. Every defendant -- even one who claimed that he was high on cocaine during most of the alleged planning sessions -- was convicted of conspiracy. The jury even convicted Nosair, who was in state prison during the entire time the plot was being put together.

According to Salem, Nosair helped to plan the attacks from his Attica state prison cell. That advice -- and several visits he received from those convicted in the World Trade Center bombing -- was enough to convict him of "seditious conspiracy."

At least three of the attorneys for the defendants said they would appeal the verdicts.

Abdel Rahman, 57, who is suffering from a heart ailment and diabetes, will be taken to a federal medical facility.

In a statement released through his attorney, Abdel Rahman said: "Anyone who has chosen this path in life has to take this in equanimity. I'm not going to be the first one to be imprisoned because of my religious beliefs, and I won't be the last one. We will persevere and continue to be a servant of God." Special correspondent Nancy Reckler contributed to this report. BOMBING, CONSPIRACY TRIALS Convicted yesterday in a conspiracy to bomb New York City sites and to commit other terrorist actions to force a change in U.S.-Middle East policy: SHEIK OMAR ABDEL RAHMAN: 57, blind Egyptian religious leader. Accused of giving approval to his followers to carry out acts of terrorism. Convicted yesterday of conspiring to bomb the United Nations and other New York landmarks. EL SAYYID NOSAIR: 39, born in Egypt and now a U.S. citizen. Worshipped at Abdel Rahman's Jersey City, N.J., mosque. Convicted of the 1990 murder of Rabbi Meir Kahane. Government alleges he consulted with his co-conspirators from state prison about bomb plans, targets, kidnapping and assassinations of political leaders. Other eight convicted: Ibrahim Elgabrowny, 44; Clement Hampton-El, 57; Amir Abdelgani, 35; Fadil Abdelgani, 32; Fares Khallafalla, 33; Tarig Elhassan, 40; Mohammed Saleh, 39; Victor Alvarez, 29. SIDDIG IBRAHIM SIDDIG ALI: 33, the alleged mastermind behind the plot to bomb the U.N. complex. Pleaded guilty in February of this year to the plot that included the assassination of Egyptian President Hosni Mubarak. Already convicted in World Trade Center bombing: MAHMUD ABOUHALIMA Egyptian-born German citizen, 34 Cabdriver, electrical contractor Role: Was frequently in apartment where bomb was built; mixed and transported chemicals. MOHAMMED SALAMEH Palestinian born in West Bank, Jordanian citizen, 26 Handyman, construction worker Role: Rented van used in bombing and warehouse for storing chemicals. NIDAL A. AYYAD Born in Kuwait of Palestinian parents, 26 Was chemical engineer at Allied-Signal Inc. Role: Provided chemical engineering expertise; wrote letter taking credit for bombing to New York Times. AHMAD AJAJ Palestinian born in Jerusalem, 28 Unemployed student Role: Brought bomb-making manuals into United States; talked to fugitive sought in bombing from jail. Trial timeline: July 1990: Sheik Omar Abdel Rahman, twice acquitted of assasination charges for the killing of Anwar Sadat, arrives in the United States from Pakistan. Nov. 5, 1990: Rabbi Meir Kahane assassinated in New York hotel. El Sayyid Nosair accused of his murder. Dec. 21, 1991: Nosair aquitted on state murder charges but convicted of assault and gun possession charges. Feb. 26, 1993: Bomb explodes at 12:18 p.m. in a parking garage beneath the World Trade Center complex, killing six and injuring more than 1,000. March 18, 1993: Abdel Rahman, associated with Jersey City mosque where bombing suspects worshipped, denies involvement in the bombing. Aug. 25, 1993: Fifteen Muslim men, including Abdel Rahman and Nosair, already jailed on charges relating to Rabbi Kahane's assassination, are charged in a plot to bomb the U. N. Sept. 14, 1993: Trade Center trial begins. March 4, 1994: Defendants Salameh, Ayyad, Abouhalima and Ajaj convicted on all charges. Jan. 9, 1995: U.N. bomb plot trial begins. Yesterday: Ten men, including Abdel Rahman and Nosair, convicted in conspiring to bomb the U.N., a bridge and tunnels. 1996: Ramzi Yousef, the alleged mastermind of the Trade Center bombing, is expected to go on trial next year. Compiled by Angela E. Couloumbis and Barbara J. Saffir SOURCE: Associated Press CAPTION: On seventh day of deliberations, jury convicted Sheik Omar Abdel Rahman and others of plot to bomb U.N. and other sites.