MOSCOW, NOV. 3 -- A leading Kremlin official hinted today that Boris Yeltsin, an ally of Soviet leader Mikhail Gorbachev in an impassioned dispute over the Gorbachev's reform policies, faces internal party discipline and could be dismissed.

Asked about Yeltsin at a news conference here tonight, Politburo member Alexander Yakovlev revealed some details about the Moscow party chief's controversial speech at a closed Central Committee meeting Oct. 21 and said, "We have our internal party affairs. If someone breaks the rules, then he breaks internal party discipline and he must leave."

Yakovlev, who is said to have come to Yeltsin's defense at the plenum, dismissed as "fantasy" reports that Yeltsin had complained about a "cult of personality and the pace of perestroika," as Gorbachev's program of restructuring the economy is called. He stressed, instead, that the outspoken Yeltsin had supported Gorbachev's reforms.

"This is not a fire," Yakovlev told reporters in an apparent attempt to douse interest in the affair, adding that the Moscow party eventually will examine the incident. "We are not in any hurry."

Yakovlev's appearance, in connection with the celebration of the Soviet Union's 70th anniversary, gave rare exposure to the influential official who is by reputation Gorbachev's strongest supporter on the Politburo and a key architect of the Kremlin policy of glasnost, or open debate.

In the wide-ranging, 90-minute news conference, the 63-year-old Kremlin propaganda chief rebuffed thorny questions with a style reminiscent of an earlier generation of Soviet officials.

Asked why Gorbachev, in a major speech yesterday, had referred to the "thousands" and not the "millions" who had suffered under Joseph Stalin, Yakovlev suggested that historical accounts of the millions purged or killed through forced collectivization under the former Soviet leader were "rumors."

Western and some Soviet historians agree that at least 7 million died under Stalin in the 1930s alone.

"Why do you think that if he had said 'millions' he would have been speaking more truthfully than if he had said 'thousands?'" Yakovlev said in reference to Gorbachev. "I know the rumors that persist in the West . . . but I think many rumors lie on the conscience of certain people."

Asked by a westerner whether then-Soviet leader Nikita Khrushchev's secret 1956 speech denouncing Stalin would finally be released publicly in the U.S.S.R., Yakovlev responded with a joke. "This has not been studied yet," he said of the controversial address, which has never been printed in this country despite the policy of glasnost. "But you shouldn't worry about it; you've gotten it all published anyway."

Faced with a barrage of other inquiries about the Stalin period, Yakovlev admitted that as a young Soviet who lived and fought in the Stalin-led Red Army, he respected the Kremlin leader. "I had faith in the belief that Stalin's leadership was correct," Yakovlev said, "and that his ideas were correct."

Yakovlev displayed a crisp language, sense of humor and direct style, marks he has apparently already left on official Soviet publications and speeches. Since he started directing the Soviet Union's massive state-controlled media, official newspapers and magazines have been made more concise and sprightly, cleaned of the heavy terminology often associated with them.

The cavalier approach Moscow's propaganda specialist took to pressing questions, however, coupled with some surprising decsions made by the Soviet leadership recently, have left some western observers feeling that the policy of glasnost, with its accents on greater criticism in the official Soviet media and more freedom of expression, is carefully controlled.

When the Soviet news agency Tass issued a statement about the party controversy over Yeltsin last week, it included an advisory on an internal wire to Soviet editors not to use the material, perhaps because it indicated disagreements in the party leadership.

Asked the reason for the decision by an American journalist tonight, Yakovlev rebuked the questioner. "Why do you use the internal Tass statements," he said, "we do not use your internal things."

Asked whether glasnost would bring more publications to Soviet kiosks, where the sale of American or Western European newspapers and magazines is restricted, Yakovlev said that more foreign periodicals already are distributed in the Soviet Union than are Soviet publications in the West.

At the same, Yakovlev advocated a program of further democratization of Soviet society.