The Kremilin leadership, in its first direct statement since the invasion of Afghanistan, today bluntly rejected President Carter's sanctions as "a hopeless undertaking that will flop" and made clear it is ready for a severe deterioration of relations as the price of its military action.

The Soviet leaders, in a lengthy unsigned statement issued through the official Tass news agency, declared that Carter's Jan. 4 speech in response to the invasion "lacks political balance, lacks real consideration of the international situation and overestimates the real potentialities of the United States" while underestimating Soviet strength and resolve.

"If the White House decided to influence in some way the Soviet Union, its foreign policy, this is a hopeless undertaking," the leadership delcared. Moscow said the president's actions will hurt the United States more than the Soviet Union, made clear the Kremlin has no intention of giving up Afghanistan, and asserted Carter acted because of his concern about this year's presidential election instead of concern for world peace.

The statement, which Tass said it was "authorized" to transmit, leaving no doubt as to its source, is the first official leadership response to Carter since the controversial hotline exchange between Carter and Soviet President Leonid Brezhnev during the Soviet-backed coup in Kabul. The leadership declaration shows more starkly than anything the Soviets have said throught their controlled media that the Kremlin does not shrink from either world condemnation or confrontation with Washington over the invasion.

"Those who ignore" Soviet resolve "always risk to blunder in politics and cause more harm to their own country [and] people than those against whom some step is spearheaded," the 14-member ruling Politburo asserted through Tass.

They warned Carter to back off, saying, "The ruling circles of the Soviet Union would like to hope that a sane, farsighted approach to Soviet-American relations, specifically to the efforts to preserve peace, will finally prevail in the U.S."

Without referring directly to previous Soviet contentions that the Marxist Kabul government sought Moscow's intervention, the leadership asserted that all know "the Afghan people alone and nobody else [have] the right to decide [their] internal development." They said Carter's sanctions speech, in which he embargoed 17 million tons of gran to the Soviet Union, cut other trade, science, and cultural exchanges, and reiterated why he sought delay of SALT II ratification, shows "gross interference in Afghanistan's internal affairs."

The Soviet leaders avoided the Soviet media's shrill personal attacks on Carter, but like earlier Soviet responses to the crises, did not indicate if the Kremlin may undertake any specific bilateral steps in response to the president's actions. There is speculation here that the leadership, deeply stung by foreign condemnation despite its tough stance, is carefully watching the U.N. Security Council debate over the invasion and the debate on the Iranian crisis before contemplating further moves.

The Kremlin leades said Carter "is heating the passions of those circles in the U.S. long displeased with detente. It looks not [like] a statement of the person holding the highest government post in the U.S., but rather that of a candidate embarking on another round of the election campaign." It said, as have the official media, that Carter used the Afghanistan situation "as all but the main pretext for this statement."

They accused Carter of using the Tehran embassy cirsis for "blackmail and threats against Iran," their "neighbor," and strongly indicated Moscow will veto any economic sanctions voted by the Security Council against Iran. In a new attempt to gain favor with Ayatollah Ruhollah Khomeini, Iran's religious leader who has strongly condemned the Moscow invasion, the leaders asserted, "Washington clearly cannot stomach the revolution made by the Iranian people, [or their] intervention to oppose imperialist policy of threats and diktat"

The Kremlin said Carter's trade and exchange cutbacks meant little since these ties "have already been limited" by earlier U.S. policy and added that the American people will frown on the embargo of grain for Soviet livestock. Americans have "many times shown they want "widening business relations with the U.S.S.R., justly beleiving this is beneficial to the U.S. itself."

The leadership declared it "never sought such ties . . . as a favor. It always stressed that [such] development, just as maintenance of good relations as a whole, is a mutual affair."

The Kremlin made no comment on the chorus of denunciation from other foreign capitals, underscoring its determination to focus on the U.S. as the principal target of its propaganda attacks. The leadership apparently hopes to find fissures between the NATO allies and Washington over the recent decision to deploy Pershing II missiles in Western Europe. The Kremlin said the United Stated had "imposed" the move on its allies.

The Soviets have refused to consider talks on missle reduction in the European theatre until the Pershing decision is reversed. From here, Moscow's position seems a calculation that a tough stance may increase the nervousness of some of the allies about the question and perhaps eventually induce them to back away from it.

The statement today made no mention of Pakistan or Soviet allegations that new American arms shipments there are aimed at supporting the Afghan rebels.