Soviet President Leonid Brezhnev declared a readiness today to negotiate an accord with the United States that would either ban or severely restrict the development of all new types of strategic armaments and called for a nuclear freeze "as soon as the talks begin."

Accepting President Reagan's May 9 proposal to resume talks on strategic nuclear arms, Brezhnev said the freeze would "facilitate" progress toward an eventual "radical limitation and reduction" of nuclear weapons.

He welcomed Reagan's initiative to negotiate a reduction of the long-range strategic arms, calling the move "a step in the right direction." Yet the Soviet leader made no mention of the June date suggested by Reagan for the talks and warned that the "essence" of Reagan's approach to arms control was "absolutely unilateral in nature" and "directly prejudicing" Soviet security interests.

The White House rejected Brezhnev's call for a freeze but welcomed the Soviet leader's "announced willingness to begin negotiations on substantial reductions in strategic nuclear arms." Story, Page A15

During his speech, Brezhnev also announced that the plenary session of the Communist Party Central Committee would open "in a few days" to deal with the nation's food problems. It was also expected that the session would consider some of the succession problems in the Soviet leadership following the deaths this year of several ranking officials.

Reagan's proposal called for the reduction of one-third of the number of nuclear warheads that the United States and the Soviet Union deploy on long-range ballistic missiles. Reagan also proposed that each country's limit of these strategic, or long-range, missiles be set at 5,000, compared to the more than 7,000 each now deploys. He also suggested that no more than 2,500 missiles be deployed on land, a difficult proposition for the Soviets since 75 percent of their warheads are land-based.

Without giving a detailed counterproposal, Brezhnev declared in a nationally televised speech that "it is necessary to preserve everything positive" that had been achieved in earlier U.S.-Soviet strategic arms limitation talks.

The new talks, he added, "do not start from scratch but a good deal of far from useless work has already been done. This should not be overlooked."

The remark was interpreted by Western diplomatic analysts here as a clear indication that the Soviets consider the 1979 Soviet-U.S. strategic arms limitation agreement (SALT II) as the basic framework for the future negotiations even though they do not expect its ratification. The insistence to preserve "everything positive" in that accord was interpreted as an indication that there was some room for compromise with the Reagan administration possibly involving a part of Reagan's proposal.

The 75-year-old Soviet leader appeared to have fully recovered from his recent illness. Addressing the opening session of a Young Communist League Congress, he spoke forcefully and seemed far more vigorous than only two weeks ago.

The basic thrust of his response to Reagan's speech suggested skepticism about American intentions. But Brezhnev used the opportunity to seize the initiative by adopting the "freeze" proposals of antinuclear groups in the United States and Western Europe and presenting it as his own plan.

He said it "is very important to effectively block all the channels for the continuation of the strategic arms race in any form. This means that the development of new types of strategic weapons should be either banned or restricted to the utmost" by agreements.

"We would be prepared to reach agreement that the strategic armaments of the U.S.S.R. and the U.S. be frozen right now, as soon as the talks begin," Brezhnev added. "Frozen quantitatively. And that their modernization is limited to the utmost.

"It is also necessary that neither the U.S.A. nor the Soviet Union take such actions which would lead to an upsetting of the strategic situation.

"Such a freeze, an important thing by itself, would facilitate both movement in the talks and a radical limitation and reduction of strategic arms."

In his speech, Brezhnev again underscored that Moscow regarded the planned deployment of U.S. medium-range nuclear rockets in Western Europe as one of the main concerns.

The United States and some NATO allies are scheduled to deploy these intermediate-range nuclear missiles in Europe in 1983 as a counterbalance to Soviet missiles. Negotiations on these arms--which have a shorter range than the strategic, intercontinental weapons--have begun in Geneva and will resume Thursday after a two-month recess.

The Soviet leader chose to cite unnamed American critics to question Reagan's sincerity and intentions in his proposal.

Reagan did not mention the MX missile, strategic bombers and intermediate-range cruise missiles, in which the United States holds the lead.

Although Reagan later said that "nothing is excluded" from the forthcoming negotiations, Brezhnev chose to ignore that remark. The Soviet leader said the proposal was "directly prejudicing" his country's security interests "above all because the United States would like, in general, to exlude from the talks the strategic arms it is now most intensively developing."

Brezhnev outlined three aspects "needed for the talks to proceed successfully and bring about an agreement":

* The talks "should actually pursue" the goal of reducing arms rather than serve as a "cover" for the continuing arms race "and the breakdown of the existing parity."

* Both sides should show "due regard" for each other's "legitimate security interests" on the "principle of equality and equal security."

* The framework should "preserve everything positive that has been achieved earlier."

Speaking about the intermediate-range missiles in Europe, Brezhnev said the Soviet Union has already begun implementing the cuts in its medium-range arsenal that he announced last March. He pledged that missiles withdrawn from the European part of the Soviet Union would not be redeployed east of the Ural Mountains within range of Western European nations.

Brezhnev also for the first time hinted that he was prepared to negotiate reductions of intermediate nuclear missiles with China. He said this issue could be discussed "only with those in whose hands are the nuclear means which are opposed by our missiles."