The Soviet Union today angrily accused President Carter of "unprecedented pressure and blackmail" in persuading the U.S. Olympic Committee yesterday to boycott the Summer Olympics here.

The official Tass news agency, charging Carter with using American athletes as pawns to advance his re-election campaign, declared that the "White House acted in the spirit of the worst times of McCathyism."

Tass said Carter had threatened the U.S. Olumpic Committee with legal and financial penalties if it did not back the boycott, and it said that "the overwhelming majority of sportsmen and broad sections of the public" in the United States opposed Carter's boycott policy.

The Tass account did not mention that the U.S. boycott was a result of the Soviet invasion of Afghanistan in late December or that Carter had fixed a deadline of Feb. 20 for withdrawal if a U.S. boycott was to be averted. The U.S. Olympic Committee said Saturday that it would send a team if Carter changed his mind.

The bitter Soviet reaction underscores the growing dimensions of the two superpowers' struggle over the games in the aftermath of the Soviet invasion of Afghanistan.

While the Kremlin leadership has kept out of the fray, the Soviet Olympic organizers are making strenuous efforts behind the scenes to hold the line on worldwide perticipation.

The Soviet Olympic Organizing Committee made no comment today on the U.S. decision, but its vice president, Vladimir Popov, speaking in Budapest, said it was regrettable and could leave the United States without any Olyumpic movement at all. He also said he did not think the U.S. decision would have any effect on other countries.

The U.S. decision, a victory for Carter in his efforts to censure the Kremlin for the Afghan military intervention, has brought the Olympic issue close to a crucial juncture as other nations begin reassessing their positions. The deadline for official application to participate is the end of May.

Aside from the United States, the most prominent nations that have decided to boycott the Games include Egypt, Saudi Arabia and Iran, but further defections seem likely inthe aftermath of the American decision, despite the Soviet efforts.

In dealing with the issue for the past three months, Moscow has mirrored the International Olympic Committee's position that international politics cannot be allowed to interfere with international sports.

Today's Tass report accused Vice President Mondale of demagoguery for telling the U.S. Olympic Committee before its vote "that the point at issue was no less than 'the future of the entire civilized wolrd.' American sportsmen, who are being sacrificed to the political intrigues of the White House, are voicing their legitimate dissatisfaction with the decision."

Yet it would be difficult to underestimate the political importance in Soviet eyes of a successful Olympics. In party literature, lectures, and the domestic news media, the leadership has hailed the choice of Moscow for the 22nd Olympiad as a triumph of the Soviet state, signaling global acceptance of the Soviet Union after six decades of capitalist-inspired machinations to exclude Russia from the world stage.

The Soviets also looked forward to worldwide television coverage and to the more than 200,000 foreign tourists expected here, with their much-wanted hard currency.

Carter's decision last month barring any further commercial transactions here by U.S. companies licensed to participate in the Moscow Olympics has been brushed aside by Moscow Olympic organizers.

In a recent interview, a senior Soviet Olympic press official, Vsevolod Sovva, said Moscow would make do without the services of such U.S. firms as Kodak and Coca-Cola.

Although NBC's multmillion-dollar Olympic television center has been stalled short of completion by Carterhs ban, Sovva said the "the full technical base" for NBC to cover the games is in place. NBC, however, has said it would follow Carter's policy on the boycott.

During the weeks of turmoil and uncertainty following Carter's original call in January for a boycott, the Soviets have carefully muted any complaint over these nuts-and-bolts matters.

They have pressed stenuously ahead to ready the capital for what once was envisioned as a glorious opening day ceremony July 19 at Lenin Stadium on the banks of the Moscow River, when Soviet President Leonid Brezhnev was expected to welcome the world to the Soviet Union. (KEY OFF)haki-jacketed crews of Olympic workers can be seen everywhere as the city emerges through the mud and slush of spring from the long winter. Restoration of monuments speeds ahead, while crews labor to finish the sports, faclities and the new Olympic villiage, a self-contained high-rise city on a fenced, carefully guarded site a short bus ride from the stadium.

This work will proceed, despite the knowledge that the Americans, intended occupants of two-thirds of the 16-story Olympic apartment house known simply as "Building Number 10" are not going to show up.(KEYWORD)