A Soviet decision to deny a visa to a top Italian scholar who is also a Communist Party member has again placed the spotlight on the Italian Communist Party's relations with the Soviet Union.

The refusal to permit Vittorio Strada, Italy's foremost expert on Soviet literature and the translator of many Russian dissidents' writings, to attend the Moscow international book fair has led to protests by Italian politicians and intellectuals.

Described by Strada as "bureaucratic arrogance," the visa denial prompted "surprise and bitterness" from the Italian Foreign Ministry and led publisher Giulio Einaudi, with whom Strada was to have made the trip, to cancel his visit to Moscow.

But the major effect of the incident has been to focus Italians' attention on the attitude of Italy's Communists toward the Soviet Union.

"There is a growing tendency to examine closely Communist reactions to any illiberal move by the Soviet Union on dissent-related questions to see if their attitude is evolving," said a Socialist.

He explained that for many Italians the Communist Party's ties with the Soviet Union are still the acid test of its commitment to liberalism and independence.

A tense eight-line statement in Saturday's Communist Party daily, Unita, which said, "We do not understand and we do not share the decision of the Soviet authorities," was criticized here as insufficient.

Strada termed it a "ritual formula" that failed to point out that he has been a party member for the last 22 years and that he has been denied entry visas to the Soviet Union since he became critical of certain aspects of Soviet society.

A second, stronger statement by the party's top cultural offical, Aldo Tortorella, called Strada "comrade" and said denying him a visa conflicts with the party's "concept of open international relations and cultural exchange."

But the anit-Communist Milan paper II Giornale said Tortorella's statement point up "the ambiguity and reticence of Italian Communists on the thorny question of ties with the Soviet Union."

Strada told the Turin daily La Stampa that the handling of his case had shown the Italian Communists' inability "to arrive at the heart of the question" by thoroughly analyzing contemporary Soviet society.

Since the Soviet invasion of Czechoslovakia in 1968, the Italian Communists have had an increasing number of differences with the Soviet Union.The party's leaders have nevertheless made it clear that they have no intention of breaking with the Soviet Union.

They insist that relations with the Soviets is no way undermine their oft-repeated commitment to autonomy as well as to a democratic form of communism that would respect all forms of pluralism.

Privately, high placed party members have admitted that they cannot go too far too fast, because a broad segment of the party's membership still nurtures strong affection for Moscow. A glance at the program for the party's two-week national festival of unity that opened in Modena Saturday shows that performers, films or sporting teams from Eastern Europe and the Soviet Union are featured on at least half the festival's 14 days, far outnumbering other foreign participants.

This year's festival also features two American musical groups, jazz musician Sam Rivers and the Santana group. A spokesman for the festival said that to the best of his knowledge this is the first time groups from the United States were included.

The denial of a visa to Stada is the second incident this year in which Soviet attitudes have affected cultural relations with Italy. In January the Soviet ambassador nearly provoked a diplomatic incident when he urged the Foreign Ministry to persuade the Venice Biennale art festival to cancel a projected exhibition on Eastern European cultural dissent.

A major Soviet exhibition of ancient Scythian gold jewelry and artifacts opened this weekend in Venice, but Soviet Ambassador Nikita Ryjov did not attend. This led to press speculation that he feared adverse reactions from the Strada case. Strada is a professor at the University of Venice.