The 400 demonstrators began their evening recently by milling around in a large square by the Kremlin wall, bearing hand-painted signs reading ''Down with the saboteurs of reconstruction,'' ''We need reconstruction,'' and ''Give status to the patriotic association Pamyat.''
But instead of moving to disperse the demonstrators, as happens swiftly during most unsanctioned demonstrations, the police ringing the group merely asked the participants to stay out of the way of traffic.
Later, the police kept traffic out of the demonstrators' way while they marched to an apparently impromptu meeting with Boris N. Yeltsin, head of the Moscow Communist Party and one of Mikhail S. Gorbachev's closest allies in the ruling Politburo.
With that widely discussed demonstration on May 6, the Russian nationalist organization Pamyat - meaning Memory - emerged from the shadowy semi-legitimacy of neighborhood meeting halls into the political limelight, putting Mr. Gorbachev's calls for openness and democracy to something of a ticklish and unexpected test. 'International Zionism' Feared
Pamyat is the first grass-roots organization to invoke the official watchword of ''glasnost,'' or ''openness,'' in support of a decidedly unofficial political agenda, in which a yearning for a return to traditional Russian values has become inextricably intertwined with a darker nationalism that sees the Russian homeland beset by enemies, chiefly ''international Zionism.''
''They are Russian fascists,'' said a Jewish woman familiar with the group.
Among the groups's declared enemies are international Zionists and Masons, who, they say, have infiltrated the Soviet bureaucracy and are seeking world domination, ''conspirators'' who want to destroy Russian national monuments and who have routed the Moscow subway system to ''make it easier to blow up government establishments,'' and rock musicians who are called purveyors of ''satanism.'' Press Denounces Movement
Now the initial, and uncharacteristically neutral, articles about Pamyat in the controlled newspapers have given way to a chorus of denunciation. It reached a crescendo in the last two days with harsh articles in Komsomolskaya Pravda, the newspaper of the Communist Youth League, and the illustrated weekly magazine Ogonyok.
But even these denunciations paid the group a glancing tribute by applauding its goals, including fervent support for Mr. Gorbachev's anti-alcoholism campaign and devotion to Russian history.
