The Soviet Supreme Court has cleared the names of three prominent Bolsheviks, Lev Kamenev, Gregory Zinoviev and Karl Radek, who died in the 1930s during the purges of Kremlin dictator Josef V. Stalin.

The court, said the government newspaper Izvestia, "is returning to these tragic figures their honor and their names" as part of the campaign to stimulate more open discussion of key issues in Soviet political life and to dismantle the system created by Stalin.The three men were as important in their time as Nikolai I. Bukharin, an old Bolshevik rehabilitated in February. But exonerating Bukharin was considered more crucial politically because his economic theories were similar in key respects to reforms being attempted by Soviet leader Mikhail S. Gorbachev.

The rehabilitation of Zinoviev, Kamenev and Radek, Izvestia made clear, was meant to reassure Soviets they would not be punished for expressing political views. Tumultuous discussion is forecast at a nationwide Communist Party conference, starting June 28, which is to debate proposals to expand the reforms.

The persecution of the old Bolsheviks, said Izvestia, "is an urgent item for today."

"We are learning democracy, mastering the rules of political discussions, also in a time of hard struggle," the newspaper said in a long article on page three under the headline, "A Return to Truth."

Zinoviev and Kamenev spent years in exile with Soviet founder Vladimir I. Lenin before he led the Bolshevik Revolution in 1917. They were elected to the ruling bodies of the Bolshevik Party after the revolution and sided with Stalin against his arch-rival, Leon Trotsky, after Lenin died in 1924.

After Trotsky was forced into exile, Stalin turned on his former allies, and Zinoviev and Kamenev were convicted of treason and executed following a show trial in 1936.

Radek was born in Poland, took part in the 1917 revolution, was accused of siding with Trotsky and expelled from the party in 1927. He was later rehabilitated and edited Izvestia in the 1930s.

He was tried again in 1937 and sent to a labor camp where he is thought to have died.

Trotsky was murdered in exile in 1940 in Mexico and has not been rehabilitated.

Izvestia, printing a detailed account of the purges and their prelude, said that "our predecessors, the people of the 20s, could not control the situation . . . and were burned up in the flames of repression."

"They preached intolerance toward the opinions of their opponents and gave birth to physical and moral terror. And the oppression of those who were left in the minority led to a situation in which one man crushed the majority.

"A lack of the very notion of personal opinion created that wild `crowd syndrome', which sanctified any tyranny in the name of the people.

"In a word, discussion has been cut off for a long time about the paths toward the building of socialism. It has been restored now, more than a half century later, and from the same place; about the paths of developing revolution, about the role of the party and about the place, of `the ruler,' " or Vozhd in Russian. Stalin was known as the "Vozhd," or supreme leader.

In reversing the decisions against Zinoviev, Kamenev and Radek, Izvestia said, "The Supreme Court, naturally, did not discuss the `party face' of rehabilitated citizens, and did not evaluate whether they were right or wrong in the old debates. But it said clearly: They are innocent before the law, state, and people."