The Soviet government news agency Tass said today that President Reagan twisted facts and defied elementary logic in defending his policy on arms control during yesterday's televised debate with Democratic challenger Walter F. Mondale.

In a dispatch from Washington, Tass renewed charges that Reagan had not shown readiness to approach the question of arms control "realistically".

Seeking to justify his rearmament program, Tass said, Reagan "overtly falsified" what the agency called the generally known facts. It described as "nonsensical" the president's claim that the United States was lagging behind the Soviet Union in a whole series of weapons systems.

"The president portrayed things in such a way as to show that the United States does not seek military superiority over the Soviet Union and that it is allegedly the Soviet Union -- and not the United States -- that is engaged in the greatest military buildup in the history of man." Tass said that it was the Reagan administration that instigated the present cycle in the arms race and that its demand for "an astronomical sum of nearly $300 billion" for the military in the current fiscal year should speak for itself.

The Soviets in particular attacked Reagan's plans for developing new space-based weapons systems and dismissed his claim that these involve only research work of a defensive nature.

Tass derided Reagan's reported contention that the so-called "star wars" program was designed to make nuclear weapons obsolete and ultimately lead to their abolition.

"On this basis," it said, "Reagan described the space-based antimissile weapons, which apparently are intended for making a first strike, as more humane."

Tass also noted that Reagan had not made any mention of Soviet President Konstantin Chernenko's specific proposals for a resumption of dialogue between the two superpowers.

"It might seem that there had been no suggestions, for instance, that the United States follow the Soviet Union's example and assume the pledge never to be the first to use nuclear weapons, that the two countries freeze their nuclear arsenals, that nuclear tests be terminated and the militarization of outer space prevented.

"As for Reagan, he failed to advance both during the debate and before, any specific proposal that would attest, by deeds rather than by words, to U.S. readiness to display a realistic approach to the issue of ending the arms race or to talks with the Soviet Union," Tass said.

The agency indirectly criticized Mondale who, it said, had argued like Reagan for a military buildup and who defended the use of force to protect U.S. interests.

However, Tass noted with apparent approval that Mondale expressed support for talks with Moscow and that he advocated a reciprocal and verifiable freeze on nuclear arsenals.

The agency also said that the president defended his policy in Central America, where, it said, the U.S. Central Intelligence Agency was waging "a secret war" against Nicaragua and where the CIA "is actually taking a direct part in a war by the Salvadoran regime against its people."