The Hitler-Stalin pact that helped precipitate World War II has disappeared along with other documents from the Soviet Union's national archives, says a leading Soviet historian and archivist.

Yuri N. Afanasyev also said that much of the state archives, the repository for memories long denied to Soviet citizens, remain closed to scholars despite glasnost, Mikhail S. Gorbachev's policy of selective openness."I don't know for a fact that the Stalin archives haven't been destroyed. I do know that some very important documents have disappeared," said Afanasyev, director of Moscow's State Historical Archives Institute since 1986 and a confidant of the Soviet leader.

"For instance, the (Hitler-Stalin) pact and the secret protocols that go with it have vanished, they're simply not in the Soviet archives," Afanasyev said of the 1939 non-aggression accord that freed Nazi Germany to invade Poland and led to the Soviet seizure of Polish territory and takeover of the Baltic republics of Estonia, Latvia and Lithuania.

"The process of democratization and accessibility of the archives is going very slowly, much more slowly than any of us want," said Afanasyev, a 54-year-old historiographer who heads an institute with 270 professors and 4,500 students housed in an ornate building in Moscow.

The Soviet Union has traditionally denied the existence of the pact's secret protocols because they would raise embarrassing questions about the historical basis for Eastern European boundaries. Recently, the Soviets suggested the original protocols and maps, copies of which were discovered in Nazi archives and published in the West, might have been lost.

For many Soviets, the first opportunity to learn the details of the pact came in an article in Sovietskaya Rossiya, one of the Soviet Union's largest newspapers, in August, following widespread independence demonstrations in the Baltic republics.

Afanasyev was asked in a recent interview about other state papers covering Stalin's conduct of the war, the Great Terror of the 1930s, the collectivization of agriculture, and the famine and purges that killed millions.

"There is no basis for assuming that the archives are untouched and undamaged. After all, a regime that murdered millions of people certainly wouldn't hesitate to destroy a piece of paper," said Afanasyev, who is a vocal advocate of perestroika, Gorbachev's policy of restructuring the Soviet economy.

Proponents of perestroika have led an effort to discredit the Stalinist regime and many aspects of its brutally imposed command economy.

Afanasyev did not say when he believed the documents had disappeared. Asked about the possibility of archives being shredded nowadays, he said it would be "very difficult," and that he knew of "nothing to sound an alarm about."

"I am the victim along with all other historians. I stand with those who suffer from the hardship of lack of access," said Afanasyev, a longtime member of the Communist Party who has kept a high profile by writing unprecedented critical items in the mainstream Soviet press.