Communist Party Will Split Up, Official Says : Soviets: Members will have to decide if they want to stay or shift allegiance to new reform movement.

The Communist Party chief of Moscow predicted on Friday that the party, for decades an unshakable monolith, is about to split and that members will soon have to choose whether they want to stay or shift their loyalties to a new democratic reform movement.

“A schism in the Soviet Communist Party is inevitable,” Yuri A. Prokofiev told a news conference.

A major plenary meeting of the national party is scheduled to open next Thursday. It is expected to discuss the impending split and also to raise a renewed challenge from conservatives to Soviet President Mikhail S. Gorbachev’s leadership of the party.

Prokofiev, considered a relative moderate in the party, said that he has also come to the conclusion that Gorbachev should no longer remain astraddle his two posts as national president and party general secretary.

“For a time it was necessary to combine the two posts. But it is very difficult,” he said. “One side starts to lose, and in this case it is the party.”

The Communist Party, with 16 million members, gave up its constitutional monopoly on power last year and has since suffered repeated defeats at the polls. Hundreds of thousands of members have defected.

Earlier this month, it was shaken up by the creation of the Movement for Democratic Reform, a liberal coalition headed by former Foreign Minister Eduard A. Shevardnadze and other well-known politicians. The movement, although it is not formally a party, has the potential to lure away masses of reformist Communists.

Prokofiev said that Shevardnadze’s movement will soon become a bona fide party, and then Communist Party members will have to decide where they stand.

The upcoming plenum will help clarify the relative strength of “rival forces,” he said, alluding to the expected battle between radicals and hard-liners.

In an indication that conservatives appear to hold the advantage, a plenary meeting this week of delegates representing Moscow’s 870,000-member party issued a declaration attacking Gorbachev’s economic reforms.

The laws that were passed recently on selling state property to private individuals are “the road to the uncontrolled transfer of public riches, accumulated through generations of Soviet people’s work, into the hands of the wheeler-dealers of the black market and foreign capitalists,” the declaration warned.

A regional party secretary from Chita went further in remarks published Friday in the daily newspaper Rabochaya Tribuna, or Workers’ Tribune.

“We must decisively reject Gorbachev’s anti-people policy,” Nikolai Merzlikin said. “The Soviet Communist Party must deny Gorbachev its political confidence. He has no right to call himself a Communist, turning the party into his hostage.”

Merzlikin said that Gorbachev’s reforms were leading to “unemployment and poverty for millions of people, and the party will be blamed for it.”

Along with their expected attacks on Gorbachev, conservative Communists are considered likely to try to expel supporters of Shevardnadze’s new movement from the party.

The plenum lacks the right to oust Gorbachev from his post as general secretary, but it could call a special congress that would have the power to vote changes in the party leadership.

Gorbachev has said repeatedly that he plans to remain as general secretary, arguing that combining the post with the presidency helps foster consensus and stability.

As conservatives mull their next moves, the party’s reformists also face a choice.

Some argue that it is time for a full split, that they must distance themselves from the Communist camp if they hope to do well in national elections expected to be called in the next year or two.

Others contend that if they split, they will be leaving all the party’s property--millions of dollars’ worth of buildings, printing presses, rest houses and the like--to the conservatives.