Released Soviet Jewish dissident Anatoly Shcharansky said tonight that during his last month's imprisonment in a Soviet labor camp he was repeatedly given massive vitamin injections and was fed a diet that added more than 20 pounds to his weight in an effort by the authorities to mask nine years of torture by deprivation.

Shcharansky said he thought he was being prepared for a visit to his mother and brother in Moscow, and did not know until the day before his release that he was part of a prisoner exchange that would lead him to Israel.

Of the fattening process that began Christmas Day in a prison camp in the Urals, 500 miles east of Moscow, Shcharansky wryly observed, "It's traditional in the Soviet system that when they produce some goods for export, they put them in a much better covering."

Describing his captivity in his first news conference since he walked to freedom Tuesday across West Berlin's Glienicke Bridge, Shcharansky said he encountered bitter hatred and anti-Semitism by the Soviet KGB, or secret police, and a constant process by the authorities to break his will, either by physical or psychological means. These included months of solitary confinement, near-starvation, threats of death and insinuations about his wife, Avital, who emigrated to Israel the day after they were married in 1974.

When the KGB began telling him "lots of dirty things" about his wife, he understood the extent to which she was working in the West for his release, Shcharansky said.

Shcharansky said he had no way of knowing about the worldwide efforts being made for his release, saying that if any of his relatives had written about the campaign, the letters would have been confiscated. He said that in "good years" he received two letters from his wife and some years none.

For more than 1 1/2 hours, Shcharansky conducted an engaging, frequently witty dialogue in English with reporters in a floodlit ballroom in the Hilton Hotel here, alternating between derision of the Soviet system and pained recollection of his years of suffering.

He said that he had adopted techniques to avert a physical or psychological breakdown, at first committing to his memory details of all of the meetings he had held in Moscow with western contacts prior to his arrest to persuade himself "that what the KGB was trying to do was practically impossible."

He said he sustained himself with thoughts of his Jewish heritage and, while locked from time to time in subfreezing punishment cells, by singing to the amusement of his guards the few Hebrew songs he had learned.

"You have to keep yourself in hand [with] special psychological exercises. Everyone must invent them for themselves. You have to choose what is important to you and repeat it every day like a prayer," Shcharansky said.

He added, "They try to isolate you so much . . . you simply forget, and the system of priorities, the system of values will change."

Shcharansky said he was never tortured in the sense of being physically beaten, but added quickly, "There is torture by the punishing cells, torture by hunger and by cold." He said that his darkest moments came during 130 straight days in solitary confinement, "when I was facing a situation in which I was getting accustomed to thinking that I would have to die."

He said that he rarely slept in the punishment cells because he had to keep moving and exercising to avoid freezing to death. Each time he was locked in the special cells, he said, he began to feel himself losing strength.

Asked whether he encountered anti-Semitism in the prison camps, Shcharansky replied that his jailers evidenced deep hatred for him as a Jewish human rights activist, and constantly tried to nurture anti-Semitism among his fellow prisoners. He described one episode in which a Jew was placed in the cell next to him, apparently as an informer, and in which efforts were made to fuel tensions between Jewish and Ukrainian prisoners. He said that when he discovered the purpose of the moves, he wrote to the prosecutor general in Moscow to complain.

"In all these years, the KGB's hatred of me increased practically every month, and they assured me every month that I would never leave that country," he said.

He added, "My release without making any concessions proves our struggle can really be successful despite all the pessimism we hear."

Shcharansky appeared to be in good health in his first meeting with reporters since his release. He had spent the day in seclusion, broken only by a visit to Jerusalem's Hadassah University Hospital to undergo medical tests conducted by Mervyn Gotsman, former prime minister Menachem Begin's personal physician. Gotsman later told reporters that Shcharansky was "remarkably fit" in view of his ordeal.

Tests showed a "very minor defect" in Shcharansky's heart, Gotsman said, and a "very mild, minor neurological defect, probably as a consequence of prolonged periods in prison." But, Gotsman said, "We're seeing here for the first time an example of a person who has had very, very rigorous psychosocial physical treatment [and] extreme deprivation, and the person we have seen today has been reconditioned for the showcase before discharge."

Sitting beside his wife while talking with reporters, Shcharansky smiled broadly and waved to friends in the audience, occasionally displaying flashes of wry humor and never evidencing signs of fatigue despite two days of whirlwind welcoming activities.

"I'm very glad that I can resume my business contacts with representatives of a free press after a long interval," said Shcharansky, who prior to his arrest was the most outspoken Jewish "refusednik" in the Soviet Union and cofounder of a committee to monitor Soviet compliance with the human rights provisions of the 1975 Helsinki agreements

When asked at one point whether he was aware that his support was being solicited by widely varying political parties in Israel, Shcharansky replied that he had been so isolated he was unaware of the political currents here. "I can tell you one thing, that the Communist Party wouldn't be able to recruit me," he added.

Asked whether he felt grateful to Soviet leader Mikhail Gorbachev for releasing him, Shcharansky replied, "Well, frankly speaking, not."

However, the human rights activist stressed, efforts should be initiated by the West -- especially the United States -- to convince the Soviet leaders that his release could be "only the beginning of a long process of improving the situation of emigration and human rights and that such a policy will really give the Soviet Union new opportunities in other fields."

[In Washington, Soviet Ambassador Anatoly Dobrynin, leaving a State Department ceremony on a new U.S.-Soviet civil aviation agreement, was asked whether Shcharansky's relatives would be allowed to leave the Soviet Union. Dobrynin replied, "I hope so," United Press International reported.]

Shcharansky said that at 11 a.m. Monday, he was sitting in the Soviet prison camp reading books by the German writers Goethe and Schiller when he was abruptly taken outside, stripped of his prison clothes and given new garments.

"I knew something extraordinary was happening. This never happened before," he said.

Asked whether he planned to visit the United States on behalf of Soviet Jewry, Shcharansky replied, "I don't have any concrete plans, but I feel deeply obliged to many people in the United States, from top officials to many housewives . . . . As soon as I have enough strength and time to make such a visit, I'll do it."

When asked his impressions of his wife's struggle for his freedom, Shcharansky said, "Frankly speaking, we haven't had time to speak about it. I think we will spend another nine years in the future discussing all these details."

But, he added, "I don't need to discuss it to know how decisive was her role in my release."