The Israeli government has begun elaborate preparations for a public trial of John Demjanjuk, accused executioner at the Nazi death camp at Treblinka, who is expected to arrive here in several days following approval yesterday of his extradition from the United States.

Demjanjuk, who will be the first person since Adolf Eichmann 25 years ago to stand trial in Israel for World War II crimes against humanity, lost his final appeal before the U.S. Supreme Court yesterday and will be prosecuted before a three-judge court in Jerusalem in several months, Israeli Justice Ministry officials said today.

Eichmann, who was kidnaped in Buenos Aires by Israeli agents and brought here for an eight-month trial, was hanged in 1962 for his role in the Holcaust in which 6 million Jews were killed.

Demjanjuk, 66, a retired Cleveland auto worker, is charged under Israel's 1983 extradition request with being a guard and gas chamber operator at Treblinka, Poland, where 900,000 Jews were executed in 1942 and 1943.

Witnesses, identifying him from photographs, have said that Demjanjuk was then called "Ivan the Terrible" and that he tortured prisoners as they entered the gas chambers, and then released the poison gas that killed them.

Some Treblinka survivors have testified that Demjanjuk killed Jewish camp workers with his bare hands and pulled young Jewish girls out of the gas chamber lines and raped them before shooting them.

Demjanjuk, a Ukrainian, contended that he was serving in the Soviet Army when captured by the Germans in May 1942, and taken to Poland. He has said he was the victim of fabricated evidence supplied by the Soviet KGB.

Demjanjuk entered the United States as a displaced person in 1952 and was naturalized six years later. The U.S. government began court proceedings in 1977 to revoke his citizenship on the ground that he had misrepresented himself.

Israeli Justice Ministry officials said they have been preparing since last June for Demjanjuk's trial. It is expected to last for months and -- as with Eichmann's -- rivet public attention on horrific recollections for an estimated 100,000 Israelis who survived Nazi persecution of the Jews during World War II.

The Ghetto Fighters' Museum at the Lohamei Hagetaot Kibbutz in northern Israel has offered to make available the same glass witness booth that was used to enclose Eichmann during his Jerusalem trial in 1961.

When asked what purpose would be served by exposing the Jewish state to another national trauma more than 40 years after the end of the war, Foreign Minister Yitzhak Shamir replied, "It's not a question of rational moves. It's a problem of historic justice, and it is very important for the future and the destiny of the people."

Shamir, who lost relatives in the Holocaust, said, "I think it is our national duty to bring to trial in Israel Nazi criminals, and we will do it, and if there are other Nazi criminals in the world, all of them will be brought to trial here in Israel."

The historic importance of such public trials, Shamir said, is especially applicable to "the education of the younger generation of our people and other peoples."

Yitzhak Feinberg, Justice Ministry spokesman, said that after a federal court in Cleveland approved Demjanjuk's deportation, the ministry began preparations for a trial, naming two task forces to establish procedural guidelines and prepare the prosecution.

Feinberg said that because Demjanjuk is charged under a 1950 Israeli law providing for the death penalty for persons convicted of murdering Jews during the Nazi rule, he will be tried before a three-judge panel headed by a Supreme Court justice. He said that only after the formal indictment is handed down will the panel decide on the exact location of the trial in Jerusalem.

Noting that Eichmann's trial did not begin until a year after he arrived in Israel, Feinberg said, "I would expect his Demjanjuk's trial to begin in a few months."

Former attorney general Shmuel Tamir said he was "certain" that Demjanjuk would receive an impartial trial and that he hoped Demjanjuk would be defended by a non-Israeli lawyer "for the sake of convincing world public opinion of the integrity of . . . such a trial."

A Treblinka survivor who said he knew Demjanjuk and last saw him the day he escaped from the camp in 1942, today described the former Ukrainian guard as a "sadist."

"I have terrible memories," Aharon Gelbart said in an interview on Israel's Army Radio. "He was cruel. There are no words to express what a sadist he was and how he had fun with his victims."