MOSCOW, SEPT. 28 -- In the debates now raging among the Soviet elite about history, culture and how far to take Mikhail Gorbachev's new policy of glasnost, or openness, conservatives have found two forceful allies in Yegor Ligachev, second only to Gorbachev in the ruling Politburo, and Viktor Chebrikov, head of the KGB security police.

In recent weeks, Ligachev has stepped up his criticism of the widening review of Soviet history that has been going on here, defending the eras of Joseph Stalin and Leonid Brezhnev as periods that did the country as much good as harm.

The 66-year-old chief of ideology for the Communist Party also has called newspaper editors to task for articles that exceed the ill-defined limits of glasnost, as he sees it, and sounded warnings against the infiltration of "mass bourgeois culture" into Soviet society.

Despite these actions, a number of western analysts here are reluctant to describe Ligachev as an opponent of Gorbachev, although some say he may be positioning himself as a potential rival. Instead, they see him exercising his ideological role, setting the parameters of the debate and drawing in those conservative elements that are alienated by Gorbachev's cultural reforms.

They note, for instance, Ligachev's broad support for Gorbachev's economic liberalization program and his reputed role in some of the early efforts to open public debate here. Ligachev last year was widely credited with the decision to release the film "Repentance," an allegorical treatment of Stalin's terror.

But as the process of glasnost moves forward, Ligachev has joined ranks with conservatives on a number of issues. Last March, he criticized the "exaggerated assessment" of long-suppressed literary works now appearing in print, aligning himself with the old guard in the writers' union who have attacked what has been called the phenomenon of "Nabokov-itis," after Russian emigre writer Vladimir Nabokov, now being published here for the first time.

Ligachev's voice was echoed by Chebrikov, who, in a major speech on Sept. 10, accused the Soviet Union's enemies of trying to force "individual representatives of the artistic intelligentsia into the position of criticism, demagogy and nihilism."

By assigning the "services of imperialism" a role in Soviet internal debates, Chebrikov was seen as again raising the specter of links between criticism and subversion, dissent and treason.

Some members of the Moscow intelligentsia view these statements by top leaders with concern bordering on alarm, while others see them as a natural extension of the debates that have been percolating at lower levels -- at public meetings, in the press and among fractious literary circles.

"People here are so used to seeing one line coming from the top that they are having difficulty adjusting to a mix of voices," said a young Soviet scholar.

Ligachev and Chebrikov were elevated to the Politburo in 1985, a month after Gorbachev became general secretary.

Ligachev has been more visible than usual in recent weeks. He has been filling in for Gorbachev, who has been out of public sight since Aug. 7. The Soviet leader, widely perceived as the Politburo's strongest supporter of cultural liberalization, is said to be on vacation, although his prolonged absence has fueled rumors that he has been ill.

In the past month, Ligachev -- who, as the Communist Party's second secretary, oversees the work of the huge party apparatus -- has kept his profile high: chairing a meeting on problems in the Soviet tea industry, meeting with a leader of the French Socialist Party, speaking to teachers on educational reform and gathering media chiefs for a discussion of preparations for the November celebrations of the Soviet Union's 70th anniversary.

History is a favorite theme of Ligachev, and it is on this subject that his remarks have had the most impact. Since early this year, He has warned repeatedly against emphasizing only the dark periods of Soviet history while ignoring the achievements.

For Soviet readers, the remarks signal a thinly disguised criticism of the growing public reexamination of Stalinism. Removing the enduring vestiges of that era is at the heart of Gorbachev's reforms, in cultural, economic and political areas. The critical assessment of Stalin has broadened recently, going beyond the legacy of his crimes to his creation of a highly centralized system of administration that has become the bane of the Soviet economy.

In a speech last month at Electrostal, outside Moscow, Ligachev again called for a balanced look at the 1930s -- the years of Stalin's brutal terror and crash industrialization program. Ligachev attacked the "cult of personality" that surrounded the Soviet dictator, but said, "In those years, the country reached second place in the world in the volume of industrial production, carried out the collectivization of agriculture, achieved new heights in cultural development, education, literature and art. This is an indisputable fact."

Such a defense of Stalinism, coming at a time when agricultural collectivization is again being acutely debated, was seen by many as cutting across lines set by Gorbachev and newly elevated Politburo member Alexander Yakovlev, who as the party's propaganda chief also deals with ideology.

In the speech, Ligachev also defended the Brezhnev era, now usually referred to in Soviet shorthand as "the period of stagnation." He called the Brezhnev years of the 1960s and 1970s a time of progress, particularly in western Siberia, where Ligachev served as party leader.

"If anyone were to ask me how I related to that period," he said, "I would answer in the following way: It was an unforgettable time, genuinely a great life." He did go on to criticize the "unrestrained accolades" that surrounded the leadership in the late Brezhnev era and the accompanying abuse of power, but Ligachev's even faint praise of that period was the first to be heard from a Politburo member since Gorbachev came to power in March 1985.

Last week, according to literary sources, Ligachev rebuked Yegor Yakovlev, editor of the weekly Moscow News, for publishing an obituary of Viktor Nekrasov, a writer and dissident who emigrated to Paris. Ligachev's reprimand came after he publicly criticized editors for publishing articles without sounding out the opinions of their editorial boards.

"It has been noticed that some editorial offices readily print that which conforms to their point of view," Ligachev said. "That which they don't agree with they either don't publish or accompany with commentary that repudiates it. The result is one-way democracy, which should be gotten rid of."

Chebrikov's speech, given on the 110th anniversary of the birth of Felix Dzerzhinsky, founder of the Soviet security police, was seen by some intellectuals here as even more alarming than Ligachev's statements, given the forces that Chebrikov heads. It also marked the KGB chief's first public comments on the loosening of restraints on Soviet life.

The speech attacked what Chebrikov called anticommunist elements in Soviet society who, he said, understand the "broadening of democracy as a possibility to do anything that comes into their heads without punishment and act against the interests of Soviet society."

As the process of democratization has picked up pace in Soviet life, the KGB has scaled back its tactics, giving freer rein to unofficial journals, discussion groups and, to a limited extent, public demonstrations. But the KGB's power is still visible, hovering at the edges of glasnost.

One example was the search on Sept. 7 of the Moscow apartment of historian Dmitri Yurasov, who had stunned a public meeting this year by disclosing secret statistics on the Stalinist repression and gruesome accounts of tortures.

According to a newly established human rights chronicle, Express-Chronika, documents pertaining to victims of Stalin's repression were seized during the search, conducted in Yurasov's absence.