Argentina's armed forces tonight officially washed their hands of blame for the disappearance of thousands of people during their 1970s war against leftist guerrillas and other dissidents here, declaring all those still missing to be either voluntarily in exile or hiding, or "considered juridically and administratively dead."

In a long-awaited official report to the nation delivered on state-run television and radio, the military government maintained that all measures taken during its campaign against subversion are considered acts of service undertaken in the line of duty.

The report declared that all those official actions that critics may have considered human rights violations, called "excesses" in military terminology, already have been punished whenever guilt has been established.

Local and international human rights organizations, as well as a number of foreign governments, have accused Argentina of one of the world's worst rights records during seven years of military rule. They have charged the armed forces with responsibility for the presumed deaths of between 6,000 and 15,000 Argentines who "disappeared" during what the military called its "dirty war" against subversion in the late 1970s.

The rights groups charge that the security forces waged an illegal campaign of kidnaping, torture and death against thousands of Argentines. Included among the desaparecidos--"the disappeared," as they are known here--are hundreds of elderly people, a similar number of pregnant women and more than 100 children under the age of 12. Few of the desaparecidos have ever returned.

Although there was no question that leftist guerrilla groups posed a severe threat to the government, the real battle against the guerrillas was considered by most observers to have been won by the end of 1976, before the bulk of the disappearances took place.

In 1978, Congress barred all U.S. military sales and assistance to Argentina because of human rights abuse. The Reagan administration, in an effort to improve relations with the military government, persuaded Congress to lift the formal ban in December 1981, but it agreed in exchange to a congressional demand that it certify an improvement in the human rights situation before any arms transfers were undertaken. Informed observers here said that tonight's report, and the military's reported official refusal to take responsibility for the disappeared, may make such certification more difficult.

Tonight's report acknowledged that a number of Argentines were missing. But it said that they either were voluntarily in exile or hiding or that they had been killed in combat or internal guerrilla strife and the military had never found or had been unable to identify their bodies. The report offered no numbers for the unidentified dead and missing.

Although it said that military members "assume the authentic pain of Christians who recognize the errors they may have committed as they complied with their orders," the report did not imply armed forces responsibility for the non-combat killing and illegal disposal of the bodies of often innocent persons, as human rights critics have charged.

The report stems from demands by civilian political leaders and the Roman Catholic Church, who had called on the armed forces to clear up the question of the disappeared as a means of national reconciliation before a new civilian government takes over following elections scheduled in October.

Initial political reaction to tonight's 45-minute government broadcast was negative. Nestor Vicente, a Christian Democratic leader, called the document "irresponsible, unilateral and grotesque."

Without accepting blame for the presumed deaths, tonight's military exposition marked "the first time a genocide is recognized by those who committed it," he said. "It's as if Hitler gave a press conference."

The Mothers of the Plaza de Mayo, a group of women who for six years have held weekly vigils in front of the presidential palace to demand answers about the whereabouts of missing children, wondered tonight in a statement if "to kidnap, torture, assassinate and lie without shame are acts of service."

The government report, it said, "doesn't contain any serious information" about the fate of the thousands who disappeared.

Earlier today, human rights activist Emilio Mignone, a well-known attorney whose daughter disappeared in 1976, expressed his hope that the report would discredit claims by some military officials in recent years that the disappearances were the fault of "autonomous right-wing groups acting without authorization." He said, anticipating a military admission of responsibility, that it "will also allow us to bring court action" against high-level military officials in the cases.

The question of the disappeared is the military's most explosive legacy, both within the country and within its own ranks. A demand for an accounting by the military, whose power here has been absolute since it took over in a March 1976 coup, would have been unthinkable until the prestige of the armed forces began to crumble during the ill-fated Falklands war with Britain last year.

The final military document was presented tonight in the form of a sort of documentary, with a narrator reading a text over scenes of fires, explosions and mutilated bodies interspersed with tableaus of Argentines peacefully at work and play. Many of the scenes of soldiers in combat against guerrilla forces and youths dancing around bonfires at demonstrations were repeated twice or more, although it was not clear if this was done to increase their impact or for lack of pertinent footage.

The document delivered tonight reportedly underwent a series of revisions in recent weeks as President Reynaldo Bignone, a retired Army general, and the three-man junta sought to hammer out an agreement that would be acceptable to the various factions within the military but would not be rejected out of hand by the civilian opposition.

The armed forces are believed to be divided between those who had only peripheral contact with the repression and thus feel unfairly compromised by an all-encompassing admission of guilt, and those hard-liners who are either unrepentant or afraid that an accurate accounting would not help their situation under the coming democratic government.

The report underscored that commands to "neutralize and annihilate" subversion initially were ordered by constitutional president Maria Estela Martinez de Peron and by provisional president Italo Luder, before the Peronist government was overthrown.

The report repeated the military's contention that the pervasiveness of the guerrillas through all sectors of Argentine society and the level of violence that they unleashed made extraordinary measures necessary. It said that 25,000 Argentines belonged to subversive organizations "of which 15,000 were combatants--that is people technically trained and ideologically fanaticized to kill." Citing almost "apocalyptic conditions," the report said, "The nature and characteristics of the way the terrorists acted, their cellular structure and compartmentalized means of action necessitated unique procedures."

The report cited armed robberies, bank assaults, kidnapings, extortion and assassination as the first wave of growing guerrilla violence.

It said the violence reached its maximum level in 1976 with 600 kidnapings and 446 assassinations. Overall, 4,150 terrorist actions--including takeovers, armed propaganda, extortion and bombing attacks--were registered.

"In a war which has such peculiar characteristics as that we experienced, where the enemy doesn't wear a uniform and his identification documents are apocryphal, the number of unidentified deaths increased significantly," the report said.

The issue of the disappeared, the report said, is being used "insidiously to shock the good faith of those who did not know nor live under the conditions which have brought us to this point."

The report said "the most typical case" of a disappeared person is one in which the missing one opted for a life in clandestinity without informing his family, who in turn "filed a complaint of a disappearance they cannot explain or if they can, do not wish to."