An Israeli court today sentenced three Jewish settlers convicted of murdering Arabs to mandatory life imprisonment, but handed down lesser sentences for 12 other members of a Jewish underground terrorist organization that operated in the Israeli-occupied West Bank for four years.

The three-judge panel sentenced 11 of the settlers to prison terms ranging from three to seven years for crimes that included the attempt in 1980 to assassinate three Palestinian West Bank mayors, the murder in 1983 of three Arab students in Hebron, the planting of bombs on five civilian Arab buses in East Jerusalem in 1984, the planting of bombs at mosques in Hebron and an unsuccessful conspiracy to blow up the Dome of the Rock Mosque on the Temple Mount in Jerusalem.

They could have received maximum terms of up to 20 years. Apart from the mandatory life sentences, those given the longest prison terms -- two defendants sentenced to seven years -- will serve no more than 41 more months once good behavior time and time already served are deducted.

Another defendant, convicted of participating in the attack on the Arab mayors, walked free from the courtroom when all of his three-year sentence was suspended except for time already served awaiting trial. Court officials said the defendant, Moshe Zar, 47, was ill and had been stabbed in an Arab terror attack several years ago.

The East Jerusalem District Courtroom turned into bedlam today after the three judges completed the reading of the sentences. Spectators hugged and kissed the defendants and some sang Jewish nationalist songs as the convicted settlers congratulated one another. Supporters from West Bank settlements proclaimed the defendants "heroes of Israel."

Supporters and attorneys for the settlers said they would press for a presidential pardon for all of the defendants. Israeli President Chaim Herzog has said that he would consider no appeals for pardon until after the sentencing, and then only on a case-by-case basis.

The 13-month trial of the settlers, in which for the first time here a group of Israeli Jews was convicted of being part of a terrorist organization, was deeply emotive for the Israeli public. The defendants were vigorously supported by leaders of the Jewish settlement movement in the West Bank and by many Israeli members of parliament from the Likud bloc and other right-wing parties.

The emotional level within the Israeli public peaked in May, when Israel released 1,150 Arab prisoners -- some of them convicted of terrorist murders -- in exchange for three captured Israeli soldiers.

Court authorities pointed out that the defendants sentenced to three years' imprisonment are eligible to have a third of their sentences reduced for good behavior, and that with 15 months already served while awaiting trial and sentencing, they will have to stay in jail only nine more months. Two of 10 other convicted terrorists, who were sentenced after plea bargaining, already have been released.

Aviva Nir, the mother of Shaul Nir, who was sentenced to life today for murder in the 1983 grenade and machine gun attack on students at the Islamic College in Hebron, jumped up and down in joy immediately after the sentences were passed.

"Why am I happy? My two sons are two heroes of Israel. God arranged everything. This will bring a lot of life. It may be life for my son, but God has other plans," she said. Her other son, Barak, received a six-year sentence for participation in the Islamic College and Arab bus attacks and the Dome of the Rock conspiracy.

Also sentenced to mandatory life terms for murder in the Islamic College attack were Menachem Livni, 38, a former battalion commander in the Army reserves who led the underground terrorist organization and was in the forefront of Jewish settlers who moved into the Arab city of Hebron after Israel captured the West Bank in 1967, and Uzi Sharabaf, 25, of Hebron and a former Israeli Army soldier.

Sharabaf is the son-in-law of Rabbi Moshe Levinger, the spiritual leader of the West Bank settler movement.

Some of the Jewish West Bank settlers in the courtroom said that the trial had radicalized settlers throughout the occupied territory and that there would be further attacks on Palestinian nationalists.

The defendants "should get medals. They were chosen by God to change the Jewish law of this country. The law is in the hands of God," said Shoshana Helkiyahu, 60, who came here from New York in 1935 and now lives in the Kiryat Arba settlement near Hebron.

"I told my son, 'Now you have to do the same as they did so that there will be more people in the Land of Israel who want to get rid of the Arabs,' " Helkiyahu said.

As they were when convictions were read on July 10, the three judges were divided in their opinions today and recommended widely divergent prisons terms for some of the defendants. Under Israeli law, the lowest recommended sentence prevails.

The relatively light sentences of three years given to defendants involved in the attacks on the Arab mayors were attributed by the judges to the court's belief that the settlers deliberately used light explosive charges in the mayors' cars with the intent of maiming but not killing them because -- by the defendants' confessions -- they did not want to create Palestinian martyrs.

The sentences -- for causing grievous bodily harm -- were for car bomb attacks that maimed two mayors, Bassam Shaka of Nablus and Karim Khalaf of Ramallah. An Israeli Druze bomb disposal expert was blinded while attempting to defuse a third bomb, at the home of El Biera Mayor Ibrahim Tawil.

Shaka, whose legs were blown off by the Jewish terrorist car bomb, called the trial a sham and said the punishments were lenient "for political reasons," The Associated Press reported. "These punishments will not stop such crimes," he said.

Some of the judges' opinions also cited the defendants' distinguished military records, and noted that some of the convicted settlers had expressed regret over their actions.

A motion has been presented in parliament by Chaim Kaufman, Likud caucus chairman, seeking the pardon and immediate release of those sentenced. But the Likud does not have a majority to carry the motion even with the support of the far-right Tehiya Party, extremist leader Rabbi Meir Kahane and the religious parties.

Geula Cohen, a member of parliament who was in the courtroom, said after sentencing that she would continue to press for pardons for all the defendants. "It is a sad day when pioneers came to be described as murderers," she said.