MOSCOW, JULY 3 -- Conservative Politburo member Yegor Ligachev won loud applause from the 28th Communist Party Congress today for a ringing defense of traditional Marxist-Leninist doctrine as Soviet leaders staked out positions on either side of the ideological barricades in this politically divided country.

The reformists fought back with an impassioned speech by Foreign Minister Eduard Shevardnadze defending the Soviet Union's opening to the West and the supremacy of "universal human values" over the Communist idea of perpetual class conflict. Shevardnadze, who is regarded as a key ally of President Mikhail Gorbachev, also denounced the "waste" of billions of rubles on the military during the 1970s and early 1980s.

The clash between Ligachev and Shevardnadze on the second day of the party congress was a dramatic illustration of the political differences in the highest ranks of the Soviet leadership. Both men were elected to the party's ruling Politburo in 1985, shortly after Gorbachev became Soviet leader, and both speak for important constituencies in the 20-million-member party.

The reaction of the 4,600 delegates to their back-to-back speeches provided a rough indication of the balance of political forces at the present party congress, the first in more than four years. Roughly two-thirds of the delegates appeared to join in the prolonged applause for Ligachev, while about one-third clapped demonstratively in support of Shevardnadze.

Just a few months ago, many observers in Moscow were writing Ligachev's political obituary. His natural allies in the Politburo were being retired one by one as Gorbachev won a series of tactical victories over his opponents. Once the party's chief ideologist and second-ranked leader after Gorbachev, Ligachev was assigned in September 1988 to the thankless task of rescuing Soviet agriculture from its chronic state of crisis.

The story of Ligachev's political resurrection is almost as remarkable in its way as the comeback of his radical-reformist rival, Boris Yeltsin. It reflects both Ligachev's skill in quietly cultivating ties with Communist Party officials around the country and a determined counteroffensive by conservatives during a period of nationalist upheavals and economic disintegration.

At a time when Gorbachev and his allies have been seeking to minimize the importance of Marxist ideology, Ligachev has presented himself as the guardian of traditional socialist values. This has done nothing to boost his popularity among ordinary Soviet citizens, which has fallen to an all-time low, but it has won him a substantial following among Communist Party activists disoriented by Gorbachev's perestroika reforms.

In his speech today, Ligachev insisted that the Communist Party would remain "Marxist-Leninist" and denounced a limited experiment with private property as ideologically unacceptable. He also took issue with Gorbachev's position that fundamental changes in land ownership are required to make Soviet agriculture productive, insisting that the principal problem is a lack of resources and investment.

"Thoughtless radicalism, improvisation and swinging from side to side have yielded us little good during the past five years of perestroika," the 69-year-old Ligachev declared.

He also made clear that he remains skeptical about the new emphasis on "universal human values" that has provided the ideological justification for many of the perestroika reforms pursued by Gorbachev. He insisted that a "class approach" is essential in the formation of local legislatures, implying that blocks of seats should be reserved for representatives of workers and peasants.

"This question of whether or not to adopt a class approach to political problems is the great divide between the radicals and conservatives," commented delegate Leonid Kravchenko, director general of the official news agency Tass.

Radical delegates expressed grudging admiration for Ligachev's forthrightness in defending socialism. "I don't agree with Ligachev at all, but artistically it was very good. It was the highlight of today's proceedings," said Vladimir Zhenin from the Ural Mountain city of Sverdlovsk, a supporter of the radical-reform party splinter group known as Democratic Platform.

Following Ligachev to the podium, Shevardnadze defended the Kremlin's decision last year to allow the former satellite countries of Eastern Europe to go their own way. He said that Soviet policy makers had been fully aware that such a stand was likely to result in the overthrow of "alien, totalitarian regimes" and the collapse of the Warsaw Pact defense alliance.

"We forecast this, we felt all this," the foreign minister told the delegates. "We felt that if there were not serious changes in the East European countries, the matter would end in tragic events."

Shevardnadze said the policy of good relations with the West would ensure the Soviet Union a "peace dividend" of 240 to 250 billion rubles over the next five years. He said that his researches into Foreign Ministry archives suggested that the country had spent 700 billion rubles more than necessary in the 1970s to achieve military parity with the United States.

"Squandering a quarter of our budget on military expenditures, we ruined the country. If things went on like this, we would have no need for defense, as a ruined country and an impoverished people have no need for an army," he said.

In Gorki Park this evening, several thousand demonstrators waving pre-revolutionary Russian flags and chanting, "Shame, shame," staged a protest rally to call for the dismantling of Communist Party power. They were addressed by a Democratic Platform leader, Vladimir Lysenko, who said that the debates at the congress gave him "no hope for the formation of a new, truly democratic party."

The congress is likely to lead to a major overhaul of the Politburo and the policy-making Central Committee, the party's two main leadership bodies between congresses. Gorbachev announced today that four senior party officials had submitted their resignations: Politburo members Nikolai Slyunkov, 61, who specialized in economic affairs, and Vitaly Vorotnikov, 64, former president of the Russian republic; non-voting Politburo member Alexandra Biryukova, 61, who was in charge of the consumer sector, and Central Committee secretary Gumer Usmanov, 58. Gorbachev said both Slyunkov and Usmanov resigned for health reasons.

In his speech, Shevardnadze indicated that he would like to withdraw from active participation in Communist Party affairs, saying that he does not feel it is necessary for the foreign minister to be a member of the Politburo. Another Gorbachev ally on the Politburo, Alexander Yakovlev, suggested Monday that he may soon retire from party politics, saying that the present congress would be his last.