he Soviet Union received President Reagan's strategic arms control proposals today with skepticism, but indicated broadly that it was prepared to consider them as a basis for resuming talks with the United States on reducing nuclear arsenals.

The government news agency Tass carried a preliminary list of Soviet reservations using largely critical remarks by various American figures. It said Reagan's speech appeared to demonstrate that he was not interested in "mutually acceptable decisions" but was rather "indicative of the United States attempts to secure for itself unilateral military advantages."

But shortly afterward, the government news agency Novosti distributed to Western reporters the text of a commentary that restated similar suspicions but said "the very fact of American readiness to come back to the negotiating table can be welcomed, for it is better late than never."

"As for the Soviet side, it is always ready for talks," it added.

Soviet sources familiar with Kremlin strategic policies said Reagan's proposals were scrutinized carefully. Moscow's response, they said, could come only after the Soviets receive "detailed explanations" of the proposals.

The sources also emphasized that "some fundamental things" from the 1979 Soviet-American strategic arms limitation treaty "would have to be retained" in the new round of talks.

It appeared doubtful that preparations could be completed by late June, when Reagan proposed that the talks open, although the Kremlin clearly would like to resume the strategic dialogue with the United States soon.

The Soviet Union was expected to advance its own package of proposals for forthcoming talks.

The first Soviet reports of Reagan's speech came 24 hours after he delivered it yesterday, proposing a two-step plan in which both sides initially would reduce by one-third their arsenals of nuclear warheads on land- and sea-based intercontinental ballistic missiles.

The Soviets were briefed on the new proposals on Saturday, when U.S. Charge d'Affaires Warren Zimmermann called on the Soviet Foreign Ministry to deliver an outline of Reagan's speech and the president's message to Soviet President Leonid Brezhnev.

Ostensibly quoting American critics of Reagan's plan, Tass gave a list of Soviet concerns saying the president's proposals aimed "at making the Soviet Union give up more than the United States."

The Tass report, from Washington, quoted several American politicians, weapons experts and press commentaries as being critical of the president's proposals. It quoted former secretary of state Edmund Muskie as saying the proposals were aimed at undermining disarmament, while the United States was attempting to achieve superiority over the Soviets.

Tass also quoted Sen. Edward M. Kennedy (D-Mass.), who criticized the fact that the Reagan plan would enable the United States to continue its rearmament program.

Moscow's concerns about the plan included its exclusion of long-range bombers and intermediate-range cruise missiles. Tass said this gave "far too little evidence" that Reagan was serious about curbing the arms race since the programs such as those developing the MX, Trident and cruise missiles and the B1 bomber would continue.

Yet the core of the president's plan--the proposed reduction by one-third in the number of warheads on both sides--appeared to be the principal concern because it seemed to suggest an entirely new focus to strategic arms control.

In previous negotiations, the two sides focused on the number of launchers, or large missiles, whose numbers could be monitored by the so-called national technical means, or spy satellites and other sophisticated electronic spying. Warheads in previous agreements were covered by set sublimits.

In the preliminary analysis here, Reagan's plan to make the warhead the basic unit of counting the strategic balance would imply on-site inspection, something Moscow has been reluctant to accept. It was pointed out, however, that Brezhnev stated publicly that he was prepared to accept some form of weapons inspection other than those provided by "national technical means." It was unclear how the verification of warheads could be accomplished, but some U.S. sources suggested a form of international supervision.

Reagan's proposal also provided that not more than half the retained warheads be land-based. The Soviets, who in contrast with the Americans, rely heavily on large, land-based missiles, see in this costs far greater for the Soviet Union than for the United States.

Neither Tass nor Novosti gave detailed accounts of Reagan's proposals. Both charged that they did not meet the basic Soviet requirement that any Soviet-American strategic arms agreements should observe "the principle of equality and equal security."

"What also makes one wary is the opinion voiced by political analysts to the effect that underlying the president's need for an impressive speech were tactical motives of current policy rather than principles of peace considerations," Novosti commentator Gennady Gerasimov said.

He suggested that Reagan's proposals were aimed at offsetting the antinuclear movement in Western Europe, where Reagan will be visiting soon.

According to diplomatic observers, Reagan's straightforward and simple formula could prove an effective way to disarm antinuclear groups in the West.

Soviet sources said privately that the plan may have a "psychological effect" in the struggle for popular opinion. It makes it almost impossible for Moscow to reject it outright.

As one source put it, the issue of arms control "is far more complex than the number of warheads." Another source described the latest U.S. proposals as a "new zero option," a reference to the president's speech last November in which he proposed the abolition of all new intermediate-range missiles in Europe.

That proposal led to the current Soviet-American talks in Geneva. According to the Soviets, the Geneva talks have not moved off dead center as a result of U.S. "intransigence." Under Reagan's proposal, the United States would not deploy 572 new medium-range nuclear missiles in Europe next year if the Soviet Union dismantled all its medium-range missiles aimed at Western Europe.

Soviet sources also showed serious skepticism toward some American assessments suggesting that the new Reagan plan marked a shift in his dealings with the Soviet Union. According to this view, "great dangers" may be hidden behind the president's conciliatory stance, and a careful study of his proposals was required before Moscow could take a definitive position.

"The president's so-called initiative," Tass said, "in no measure affects the whole complex of strategic nuclear weapons, but draws only one narrow aspect from it."

Despite all reservations, Novosti noted that "the president expressed himself for dialogue . . . . The Soviet side expressed itself for dialogue with the new U.S. administration in February of 1981, a month after he assumed office."