A makeshift court inside Yasser Arafat's compound convicted and sentenced four Palestinians on Thursday for last year's killing of Israeli Tourism Minister Rehavam Zeevi, a senior aide to the Palestinian leader said.

Israeli Prime Minister Ariel Sharon immediately dismissed the decision, and a Palestinian human rights activist condemned the trial as unfair.

With security officers acting as judges and lawyers, the four men were sentenced to jail terms ranging from one to 18 years, and Arafat approved the sentences, Nabil Abu Rdeneh said from inside the shell-shattered headquarters where the trial took place.

``President Arafat approved the decision of the military court that took place in the compound a few days ago,'' Abu Rdeneh said. ``This decision does not accept any appeals after the president's approval.''

The makeshift military tribunal sentenced gunman Hamdi Quran to 18 years in prison and his lookout Basel Al-Asmar to 12 years. Getaway driver Majdi Rimawi got an eight-year term, while Ahead Gholmy was jailed for one year for having knowledge of the plot but not informing Palestinian authorities.

Under interim peace accords, Palestinians are to extradite suspects to Israel — unless they put them on trial in Palestinian courts. Since the accords were signed in 1994, the Palestinians have never extradited terror suspects to Israel.

Israel has said it would not lift its siege on Arafat's compound until the wanted Palestinians hiding inside, including the suspected assassins, were turned over and brought to justice. Zeevi was shot in a Jerusalem hotel on Oct. 17.

``I have to say, it would have been possible to avoid trying them twice, as they will anyway be brought to trial in Israel,'' Sharon told reporters during a visit to Jerusalem by the Turkish and Greek foreign ministers.

``Israel stands by its demand for the extradition of the murderers of minister Zeevi,'' Sharon said. He also said Israel continues to demand the extradition of Fouad Shubaki, the key suspect in the Karine A. arms-running scandal involving a ship carrying 50 tons of weapons, allegedly from Iran, intercepted by Israeli authorities.

The appointed judge in the trial was a Palestinian security official with no legal experience, and a policeman in the compound was assigned as defense attorney. Proceedings began Monday.

The trial was held in a compound surrounded by Israeli soldiers that often lacks electricity. Even in better times, however, Palestinian security trials often were quick, one-session affairs like that of the suspects in Zeevi's death.

``The state security courts are operating in contravention of international standards for fair trial, with people being tried and sentenced within hours,'' said Palestinian human rights activist Bassem Eid. ``The biggest violation is that convicted people have no right of appeal.''