Buenos Aires — In downtown Buenos Aires, Argentines are lining up to see the old Costa-Gavras movie ''Z,'' which shows what happens to corrupt armed forces when they get tied up in the assassination of political opponents.
In ''Z,'' the military is Greek and the time is the 1960s, but the Argentine audience identifies with the allegory. When a judge hands out heavy prison sentences to the film's guilty colonels and generals, the movie house fills with applause.
Suddenly calls for a judgment of Argentina's own armed forces are growing louder. The new intensity of demands for investigation into Argentina's human-rights violations of the late '70s comes as the military's prestige is at a post-Falklands war low.
The most visible pressure on the military to account for its actions came last week in a demonstration through the streets of Buenos Aires that drew an estimated 10,000 marchers.
But a small knot of the marchers have been hammering away at the nation's military leaders for years. The ''Mothers of May,'' named for the plaza where they demonstrate every Thursday, are protesting the ''disappearance'' of their own children and grandchildren. For five years, the women have been asking where their their relatives are. Many of the relatives appear to have been kidnapped because they were sons or daughters of political dissidents.
''All we are asking for is that the rule of law is reestablished and that the guilty are brought before the courts,'' says Emilio Mignone of Argentina's permanent assembly on human rights.
Many of the Mothers of May assume that most of the ''disappeared'' are dead - a conclusion shared by the Organization of American States, which in 1979 sent a commission to Argentina to probe human-rights violations.
Human-rights groups estimate that between 20,000 and 30,000 Argentines ''disappeared'' after a 1976 coup. The groups say the missing are scientists, writers, and trade unionists, and others - but not guerrillas. They also say hundreds of children are missing. Some of the mothers hope their relatives are alive in secret prison camps or that their missing children have been adopted.
''If only one of them is alive we want to know where he or she is. If they are all dead, then it is genocide on a monstrous scale. Either way the military have to answer for their crimes,'' says one mother.
The military, however, is in no mood to accept an investigation. It has banned reporting on human rights by state-controlled radio and televison. It has resurrected legislation that lays down minimum prison sentences of three-to-eight years for newspaper reporters who write stories detrimental to ''social peace'' and ''institutional order.''
''The armed forces will not allow themselves, under any pretext, to stand accused on account of human rights, which they have always defended,'' new Navy chief and junta member Adm. Ruben Franco warned.
The clampdown on reporting also comes in the wake of embarrassing revelations about the military. Former Treasury Secretary Juan Alemann allegedly revealed to a newspaper that the military is connected to the disappearance of two senior Argentine diplomats, Elena Holmberg and Hector Hidalgo Sola, from Buenos Aires in the late '70s. He is said to have said former junta member Adm. Emilio Massera may be linked to their disappearances. He also is said to have revealed that Massera was one of several senior Argentine officers who were members of the Italian pseudo-masonic organization P-2.
Alemann is believed to be supported by some Army officers seeking to settle old scores between the military branches. Whatever the motives, his statements about the disappearances of the diplomats were swiftly taken up by the media to widen the scope of debate on human rights, a subject that has been virtually taboo here since 1976.
Some minority political groups - among them the Socialist Party and the left wing of the Peronist movement - have now given support to the organizations and demanded trials of those guilty of torture and murder. One outspoken Peronist recently suggested that some military officers should be hanged.
But other political groups have not spoken. ''The politicians are reluctant to jump on the Alemann bandwagon because they suspect it might finish off any chances of returning to democracy,'' says political commentator Joaquin Morales Sola.
Most politicians, however, are said to feel that the problem of the disappeared should be resolved by the time they come to power, even if the only feasible solution turns out to be a pact with the military.
Some members of the armed forces are believed to be discussing an amnesty law. It would let officers involved in repression off the hook in return for an amnesty for political prisoners and some Argentine exiles.
Such a law is strongly opposed by the human rights organizations as morally unacceptable. Some officers also oppose the concept, suggesting that an amnesty for political prisoners and exiles could lead to a resurgence of guerrilla activity.
Opinions on the human-rights issue are seemingly irreconcilable. Yet many political observers here say that the longer the debate rages without a solution , the more likely emotions will grow more extreme.
When the military took power in 1976 they hoped that the brutal tactics they adopted to ''solve'' the problem of terrorism would be quickly forgotten. The problem for the junta now is that there are too many Argentines who are beginning to remember.