Soviet leader Yuri Andropov accused President Reagan today of deliberately lying about Soviet military strength and of "attempting to disarm the Soviet Union in the face of the U.S. nuclear threat."

The Soviet leader, responding to Reagan's nationally televised speech Wednesday night on military policy, said the president's strategic proposals were not only "irresponsible" but also "insane," and he charged that "the present administration is continuing to tread an extremely dangerous path."

Andropov's comments were made public by the official news agency Tass in an English-language text of an interview to be published in Sunday's editions of Pravda, the official party newspaper. The interview contained some of the strongest personal attacks on a U.S. president by a Soviet leader in recent years.

Veteran observers here could not recall a Soviet leader publicly accusing an American president of lying. The tone of Andropov's remarks was angry, and that tone and the contents suggested that Moscow has practically abandoned hope of reaching an accommodation with Washington during the Reagan administration.

Andropov, who resumed his official activities yesterday after several days of medical treatment for what some diplomats and Soviet sources reported was a kidney ailment, specifically denounced Reagan's plan to switch to a nuclear deterrent based on an anti-ballistic missile defense as a violation of earlier U.S.-Soviet treaties.

If such a strategy were to be adopted, Andropov said, it would "open the floodgates to a runaway race for all types of strategic arms, both defensive and offensive."

The Soviet leader asserted that the existing "military strategic parity" deprives the United States "of a possibility to blackmail us with the nuclear threat. This parity is a reliable guarantee of peace, and we will do everything to preserve it."

Andropov seemed to be indirectly forecasting a new wave of Soviet arms modernization to counter Reagan's rearmament program.

Responding to a question as to what conclusion he had drawn from Reagan's speech, Andropov said:

"My answer will be short and forthright: The incumbent U.S. administration continues to tread an extremely perilous path. The issues of war and peace must not be treated so flippantly. All attempts at achieving military superiority over the Soviet Union are futile. The Soviet Union will never allow them to succeed. It will never be caught defenseless by any threat.

"Let there be no mistake about it in Washington. It is time they stopped devising one option after another in the search of the best ways of unleashing nuclear war in the hope of winning it. Engaging in this is not just irresponsible, it is insane.

"Although the president spoke first of all about the Soviet Union, this speech affects the interests of all states and peoples. One should come to realize that the American leaders are trying today to turn European countries into their nuclear hostages. Washington's actions are putting in jeopardy the entire world."

The Soviet leader, recalling Reagan's use of aerial photographs of construction in Grenada on an airport that he contends could be used for military purposes against the United States, said Reagan used "a photograph of a civil airport in a Latin American country" in an effort to portray it as a threat to American security. Yet he said the president ignored the existence of U.S. military bases around the Soviet Union and the North Atlantic Treaty Organization's 1.5-to-1 advantage over the Soviet Union in the number of nuclear warheads.

"He told a deliberate lie when asserting that the Soviet Union does not observe its own unilateral moratorium on the deployment of medium-range missiles," Andropov said.

The Soviets announced last March that they would unilaterally freeze the deployment of medium-range SS20 missiles in Europe, but the United States repeatedly has charged that the Soviets are continuing to deploy them.

Although Tass in its official English version accused Reagan of telling a "deliberate lie," the Russian-language version used the words zavedomuja nepravda, which translate as "deliberate untruth" rather than the harsher Russian word lozh, which means "lie."

It is considered extremely unlikely that the Tass English translation of the leader's remarks was inaccurate. Political observers here believe the word "lie" was deliberately used for foreign audiences while the somewhat more neutral word nepravda is used in the Russian media.

The Soviet leader said Reagan's announcement of "large-scale measures to create qualitatively new systems of conventional weapons" would ensure that "another direction in the arms race is opening up."

Reagan's plan for a new "defensive" strategic conception requires a "special mention," Andropov said. He said the notion was a ruse that "laymen may find even attractive" because it "seems to be a defensive measure."

"In fact, the strategic offensive forces of the United States will continue to be developed and upgraded at full tilt and along quite a definite line at that, namely that of acquiring a first-strike nuclear capability. Under these conditions, the intention to secure for itself the possibility of destroying with the help of the ABM defense the corresponding systems of the other side, that is of rendering it unable to deal a retaliatory strike, is a bid to disarm the Soviet Union in the face of the U.S. nuclear threat."

When the United States and the Soviet Union embarked on arms control efforts, Andropov said, "they agreed that there is an inseverable interrelationship between strategic offensive and defensive weapons." He pointed out that "it was not by chance" that the Anti-Ballistic Missile Treaty of 1972 was signed "simultaneously" with the first treaty on limiting strategic offensive weapons, SALT I.

"Today, however, the United States intends to sever this interrelationship."

The interview suggested that the new Kremlin leadership has gone back to positions of last October when the late president Leonid Brezhnev signaled a shift toward a confrontational attitude toward the United States and did so in response to behind-the-scenes criticism by the armed forces chiefs.