The new Soviet leader, Mikhail Gorbachev, today carried out a major reshuffle of the Kremlin leadership, promoting three close political associates to full membership in the ruling Politburo.

Gorbachev, addressing a one-day meeting of the Communist Party Central Committee, also outlined his program on foreign and domestic policies, including modernization of the economy, and made his sharpest attack on the United States since becoming party leader six weeks ago.

Speaking on the day that the first round of arms limitation talks ended in Geneva, Gorbachev accused the United States of "violating" a Soviet- American agreement that opened the way for the resumption of those talks last month.

The Politburo promotions were approved by the Central Committee and appear to consolidate further Gorbachev's preeminent position, giving him a comfortable voting majority in the ruling council to push forward his economic modernization program.

Promoted to full membership in the Politburo, which had been depleted by the deaths of a number of old guard leaders during the past two years, were Yegor Ligachev, 64; Nikolai Ryzhkov, 54, and Viktor Chebrikov, 61. All were proteges of the late Soviet leader Yuri Andropov, who was Gorbachev's political mentor.

Gorbachev forecast substantial changes in the Soviet economy and society, calling for introduction of elements of market economy in the system. Such changes were needed, he said, because the "fate of the country and the position of socialism in the world" depended on them.

In foreign affairs, he emphasized the principle of continuity and made a friendly bow to China, saying the Soviet Union seriously wanted a "real" improvement in relations with Peking.

But he attacked the Reagan administration, accusing it of "sabotaging" all Soviet peace efforts.

The agreement to resume the Geneva talks, which Gorbachev accused the United States of violating, was negotiated last January by Secretary of State George P. Shultz and Soviet Foreign Minister Andrei Gromyko. It established a link between medium-range and strategic weapons on one hand and space weapons on the other, saying all three areas would be "considered and resolved" in relation to each other.

The completion today of the first round of the Geneva talks, he said, "already gives grounds to say that Washington does not seek agreement with the Soviet Union." This conclusion, he said, rests among other things on the "fact" that the United States "refuses in general to discuss the question of preventing the arms race from spreading to space simultaneously with the questions" dealing with strategic and medium-range weapons.

"Thus," he said, the United States "violates the accord reached in January on the interconnection of the three subjects."

This was the first authoritative comment on the Geneva talks and Gorbachev coupled it with charges that the Reagan administration was pursuing the arms race to gain military superiority over the Soviet Union. "We have told the American side more than once that such ambitious plans are hopeless," he added.

However, the Soviet leader left the door open to eventual progress at Geneva, saying this could be done if Washington "corrected" its present policy.

Today's promotions caught many domestic and foreign observers by surprise and were assessed as a clear indication of how swiftly Gorbachev is consolidating his power.

Chebrikov was appointed by Andropov to run the KGB in December 1982. The next year he was elected a nonvoting member of the Politburo.

Most spectacular were promotions of Ligachev and Ryzhkov, both brought to full Politburo membership without first having been nonvoting members.

Well-informed sources said the promotion made Ligachev the second-most powerful man in the party. Apart from continuing to supervise personnel policies, he was expected to take over the ideological portfolio, becoming, in effect, the "second secretary" of the party.

The addition of the three men raised the number of full Politburo members to 13, with six nonvoting members, and decisively shifted the balance of power in the ruling body in Gorbachev's favor.

Others promoted earlier to the Politburo by Andropov include Geidar Aliyev, 61; Vitaly Vorotnikov, 59, and Mikhail Solomentsev, 71. With veteran Foreign Minister Andrei Gromyko, 75, who has consistently supported Gorbachev, the new Soviet leader can count comfortably on at least eight of the 13 members in the ruling council.

Politburo members who were promoted to the ruling council by the late Soviet leader Leonid Brezhnev include Viktor Grishin, 70; Dinmukhamed Kunaev, 73; Nikolai Tikhonov, 79; Vladimir Shcherbitsky, 67 and Grigori Romanov, 62.

There were no changes in the Kremlin leadership during the 13-month rule of Gorbachev's predecessor, Konstantin Chernenko, who died last month.

Other promotions made today included that of Marshal Sergei Sokolov, 73, the defense minister, to nonvoting membership in the Politburo, and the appointment of Viktor Nikonov, 56, as one of nine secretaries of the Central Committee.

Nikonov is expected to take over the agricultural post in the secretariat, a job once held by Gorbachev.

Gorbachev's pronouncements on domestic affairs echoed the themes struck by Andropov during his 15 months as Soviet leader.

Gorbachev forcefully restated his determination to modernize the economy and society through improved management, fiscal incentives, discipline, a measure of economic decentralization and a consistent effort to apply modern technology to industry.

While saying that the principle of continuity also held in domestic affairs, he insisted that the "Leninist understanding of continuity implied constant movement forward and removal of everything that stands in the way of development."

He said he would push for a comprehensive change in the mechanism of economic management -- a Soviet code for introducing elements of market economy. Andropov's economic "experiments," he said, have produced "good results" but the country now has reached the stage when "we have to move from experiments to the creation of a comprehensive system of economic relations and management."

Implicitly criticizing Brezhnev, Gorbachev said that "earlier we did not make timely assessments of changes in the objective conditions of production and the need to hasten its intensification as well as changes in economic methods. We have to draw the most serious conclusions because the historic fate of the country and the positions of socialism in the world to a great extent depend on how we are going to proceed with our actions in the future."

Gorbachev complained about shoddy production, bad planning and badly calculated investments. He called for a "mandatory and serious improvement in the system of management and the economic mechanism in general."