%TAs preparations get under way for next week's meeting of nonaligned heads of state in Cuba, Yugoslavia has stepped up its press attacks on the Soviet bloc for allegedly trying to divide the nonaligned movement and manipulate it.

The Soviet Union, Czechoslovakia, Poland, and East Germany have been singled out for criticism in Yugoslav press commentaries publicized abroad through the official news agency Tanjug.The commentaries reflect concern in Belgrade at what are regarded here as Cuban-inspired attempts to tilt the movement toward Moscow.

The summit, for which preliminary meetings began today in Havana, is developing into a clash between two charismatic revolutionaries -- Yugoslavia's Josip Broz Tito and Cuba's Fidel Castro, and their different views on international relations.

Both men came to power through guerrilla campaigns but while Marshal Tito was the first Communist leader to break away from the Soviet bloc, Castro has become ever more closely identified with Kremlin policies.

The Yugoslavs are worried that Castro is seeking to take over leadership of the nonaligned movement, if not now then after Tito's death. Such a development, it is felt here, would have serious implications for Yugoslavia's independence.

This is why Tito, 87, has launched a broad diplomatic offensive aimed at preserving his definition of nonalignment as an independent force in world affairs. He has made three trips abroad this year -- to the Soviet Union, the Middle East, and North Africa -- and has received a stream of nonaligned leaders.

In an interview with the official Yugoslav newspaper Borba, Tito condemned the Cuban view of "a natural alliance" between the nonaligned movement and the communist bloc because of their common opposition to imperialism and colonialism.

"The nonaligned movement is not, and cannot be, either a conveyor belt or the reserve of any bloc. That is incompatible with the basis of nonaligned policy," he said in a clear reference to Cuba.

These warnings have been echoed more bluntly by the Yugoslav press in fresh polemics with its Soviet-bloc neighbors. A Borba commentary accused the Soviet news agency Tass of using vocabulary smacking of the Kremlin's campaign against Yugoslavia after 1948 in distinguishing between "progressive" and "conservative" nonaligned states.

Other commentaries said East European newspapers were trying to attach special political importance to Cuba's role as host of the summit and were degrading President Tito's position as the sole surviving founder of the nonaligned movement.

Particular alarm has been expressed here at a commentary by the Czechoslovak party weekly Tvorba that the movement would not have attained its present prestige without the support of the socialist community. For the Yugoslavs, such a conception of nonalignment defeats one of the main purposes of the exercise -- keeping the Soviet bloc at a distance.

According to an authoritative foreign policy commentator for Radio Zagreb, Milika Sundic, roles for "a campaign against nonaligned countries" were distributed at a conference of Communist Party secretaries in East Berlin attended by Cuba and Vietnam.

Yugoslav officials have expressed confidence that they have succeeded in awakening "the silent majority" within the movement to the threat of Soviet infiltration. They have proposed sweeping changes to a Cuban draft communique which contains detailed criticisms of Western countries, particularly the United States, but only praise for the Soviet Union.

It is understood that Tito, who will be leading the Yugoslav delegation at the summit, will arrive in Havana this week for private talks with Castro before other presidents gather.

One of the potentially stormy issues concerns Cambodia. The Yugoslavs, who see a parallel between the Vietnamese invasion of Cambodia and possible Soviet meddling in the Balkans, have pledged full support for the former Pol Pot regime -- but the pro-Soviet faction led by Cuba and Vietnam is supporting the claims of the new Phnom Penh authorities for seating at the nonaligned summit.