Communist Radicals Fight Party Ouster : Soviet Union: Some Democratic Platform members urge formation of a new party.

Radical reformers within the Soviet Communist Party responded angrily Wednesday to efforts by the party leadership to oust them from its ranks, and some appealed to other members to join them in an immediate break and the formation of a new party.

While some members of the Democratic Platform, the principal target of the new campaign, said they will fight from within the party any attempt to purge them, others declared that the time has come to quit the Communist Party and found their own.

“We call upon all Communists to leave the party, to stop paying dues and to join the new party of the Democratic Platform,” Igor Chubais, a leading member of the group, said, urging radicals to preempt the planned party action against them.

An open letter from the party’s policy-making Central Committee attacked the Democratic Platform as opposing socialism and undermining the party’s authority.

“The time has come to decide what to do about those who put themselves outside the party,” said the letter, which was published on the front page of Soviet newspapers Wednesday. “How can they stay in the Communist Party of the Soviet Union?”

Although the letter had been softened before publication while under review by party officials from around the country, Chubais contended that it shows that there has been “a conservative coup” led by Yegor K. Ligachev. He is the foremost conservative within the party’s ruling Politburo and the original advocate of such a “cleansing” of party ranks. This means in turn that “democrats should pull out before they are purged,” Chubais said.

Chubais added that he was expelled from the party by his local party organization Tuesday, even before the official publication of the letter. In Byelorussia, one of the most conservative regions of the country, the party leadership announced a purge of Democratic Platform members, including the dissolution of party groups in which they predominate.

But two other members of the Democratic Platform’s coordinating council said that, for the moment, their supporters should remain within the Communist Party and oppose the new efforts to “cleanse” its ranks of radicals.

“This letter is quite alarming since many party members will take it as a signal for a walkout from the party,” Igor A. Yakovonko said. “To my mind, however, this is not the thing to do--not yet. Party members should continue their struggle within the party for democracy.”

Vyacheslav Shostokovsky, rector of the Moscow Higher Party School and another founder of the Democratic Platform, also said that many Communist Party members wanting a broader scope and faster pace for political reforms are ready to quit and form a new party.

Shostokovsky, too, argued that the radical reformers should remain in the party.

“The supporters of the Democratic Platform have no intention to wage a fight against the party,” Shostokovsky contended. “Our goal is a democratic renewal of the party aimed at adapting it to a multi-party political system . . .”

The Democratic Platform, which was first organized in Moscow last October and established on a national basis in January, now says it has more than 100,000 members in chapters across the country. Once made up mostly of intellectuals, it says that it is now attracting significant numbers of workers.

Members of the Democratic Platform have been debating almost since its inception the questions of whether, when and how to quit the Communist Party, and sentiment is growing for a break before the party congress in July. The group will meet later this week to decide how to respond and whether to bring forward a congress planned for late May.