Georgy Arbatov, a senior adviser on U.S. affairs to Soviet leader Yuri Andropov, said today that Soviet-American arms talks are now in a "critical" phase and that if they fail to produce a "noticeable headway, then there would be no way of stopping a new spiral in the arms race."

Arbatov appeared to hold out the hope that the Reagan administration would come forward with "honest" new proposals. But he said that speculation about new U.S. ideas for an "interim solution" at the Geneva talks--"judging by what is said about them"--suggests a "new propaganda trick" to secure the deployment of new American nuclear missiles in Western Europe.

The Soviet Union, he said, would never "bless" such a move and would respond by developing "new rockets" to prevent the United States from acquiring strategic superiority.

Furthermore, he said, to maintain equality the Soviets would establish their own weapons "near American borders." He did not elaborate.

An editorial in Friday's Pravda, distributed Thursday night by the government news agency Tass, said, "A timely and effective answer will be given to the growth of the threat to the security of the U.S.S.R. and its allies, which the new American missiles in Western Europe would constitute."

Western sources attributed the firmness and explicitness of Arbatov's warning today to an improved Soviet capability as a result of the reported successful test of a Soviet cruise missile last year.

Last week, Defense Secretary Caspar W. Weinberger, in his report on Soviet military power, stated that the Soviets have begun test flights of "a new generation of ground-, sea- and air-launched cruise missiles, missiles with nuclear capability with ranges in excess of 1,600 kilometers (960 miles), significantly expanding the flexibility of Soviet strategic options."

Arbatov, however, did not unequivocally rule out the possibility of an interim agreement in Geneva and he asserted that "we will be a reliable partner in any honest talks and agreements" whose aim is detente and arms control.

Marshal Nikolai V. Ogarkov, chief of the Soviet General Staff, acknowledged in an interview with The New York Times published Thursday that land-based Soviet missiles in silos are becoming vulnerable to attack. "In order to avoid the negative consequences of such changes for peace and security, we need talks and agreements on limitation of armaments," he said.

Ogarkov also said that if the missiles planned for deployment in Western Europe were used against the Soviet Union, Moscow would directly attack the United States. He denied, however, that the Soviet Union has adopted a "launch-on-warning" policy.

Although Arbatov's article in the Communist Party newspaper Pravda was brimming with skepticism about the Reagan administration's intentions and policies, he nevertheless voiced the hope that President Reagan could be pressured by American and West European public opinion to modify his positions significantly.

Arbatov did not break any new ground in his article, which constituted a comprehensive account of Soviet views and whose publication was linked by observers to the current freeze debate in Washington and the scheduled meeting in Brussels of the NATO nuclear planning group.

Underlying Arbatov's arguments were two Soviet concerns. One is that the Reagan administration was interpreting the outcome of the recent West German elections as an endorsement of the missile deployment due to begin in December. The other is that the time for a meaningful dialogue with Washington may be running out in the context of U.S. domestic politics if the Americans do not advance new proposals in Geneva before the summer.

Arbatov, who is director of a government think tank on North American affairs and who is close to Andropov, assailed the entire foreign and domestic record of the Reagan administration. He said some of Reagan's arms control experts were in need of "medical attention," while others were ignorant. Arbatov singled out Reagan's nominee to head the U.S. Arms Control and Disarmament Agency, Kenneth L. Adelman, as being personally hostile to arms control.

Many top administration officials, Arbatov said, hinting that these include the president himself, are "a product of propaganda in its very pure form--and second-rate products at that." As a result, the administration is preoccupied with propaganda at the expense of substance.

He said that the American positions at both sets of the Geneva talks--one dealing with medium-range nuclear weapons in Europe and the other with strategic arms--were "dishonest." But the main focus of his article dealt with the medium-range missile talks where Reagan had tabled the so-called "zero option."

Under Reagan's proposal, the United States would forgo the deployment of 572 Pershing II and cruise missiles if the Soviets scrapped all their medium-range nuclear missiles in the European theater.

The Soviets have described this as a request for "unilateral disarmament." They have proposed to reduce the number of their medium-range nuclear missiles in Europe to 162, or the combined total of the French and British nuclear arsenals.

Although he stressed the possibility of reaching a meaningful agreement, Arbatov did not predict that it would become a reality. He said the Reagan administration's "anti-Soviet hysteria" makes it impossible to believe that its policies would change for the better. He also said that the administration's reported new proposals, under which the number of U.S. missiles to be deployed in Europe would be scaled down in exchange for cuts in the Soviet arsenal, represented a phony compromise.

The U.S. administration, he said, is determined to deploy these weapons in Europe to tilt the strategic balance. "One cannot forbid the present administration to pursue its goal. But it will never succeed in convincing the Soviet Union to bless such attempts."