The reopening of investigations into two alleged political assassinations has led to a public outpouring of accusations and criticism here against Argentina's military for its violent campaign against its opponents during the 1970s.

In what appears to be the beginning of a long-delayed national debate over the military government's activities, a series of former public officials have spoken out on the cases of two Argentine diplomats who were abducted in separate incidents while working for the government. Family members and human rights groups have linked military forces to both cases.

The charges and a wave of publicity have prompted a federal judge to reopen the case of Elena Holmberg, a former official of the Argentine Embassy in Paris whose body was found floating in a river outside Buenos Aires in December 1978. It has also been reported in the media here that a federal judge is reviewing the case of former ambassador to Venezuela Hector Hidalgo Sola, who was abducted in 1977 in Buenos Aires. He is presumed dead, although his body never has been found.

While both cases have been investigated before and are well known to international human rights organizations, the new probes have stirred widespread public controversy and the first public airing in Argentina of evidence of the military's alleged participation in political assassinations and abductions, or "disappearances."

Newspapers have begun describing secret prisons used by the military and have named a number of military officers allegedly involved in political assassinations. As the scandal has taken hold, family members, politicians and journalists have also strongly renewed calls for investigations of other disappearances unreviewed since the 1970s.

After three weeks of such outcries, the ruling military junta has reacted by prohibiting state-controlled television and radio stations from broadcasting any further reports of the Holmberg and Sola cases or the topic of disappearances in general.

In a signal of the armed forces' concern over their weakened political position, the edict last Friday also banned discussion of other recent charges of government corruption and criticism of the military invasion of the Falkland Islands. A sharp communique from the junta warned that it "will take all the legal measures necessary to protect military, police and security forces from false statements, intentionally distorted declarations, slander or other public expressions which affect its members."

The sudden outburst of public discussion over the estimated 6,000 to 15,000 disappearances in Argentina since the 1976 military coup is regarded by both government and political leaders here as crucial to the fate of the military government and its plans to return Argentina to some form of democracy by early 1984.

While the armed forces remain politically divided, they are nearly unanimous in a determination to avoid investigations of their conduct during the "dirty war" against Argentina's leftist guerrillas and other activists between 1976 and 1979, according to a variety of sources here. Military officials have said they are preparing an amnesty law that would excuse what they concede were "excesses," but decline to elaborate.

Members of the three-man junta and President Reynaldo Bignone have encouraged the new court investigations and have said all evidence of such crimes should be handled by the civil courts, which in the past have failed to take action in disappearance cases.

But a number of political leaders and former officials of the military government now say that the sudden emergence of the most notorious disappearance cases as a public issue could force a more serious treatment of human rights violations.

The controversy over the human rights cases erupted at a time when the military, government officials and politicians were already preoccupied with failures in the Falkland Islands war and economic policy and alleged financial mismanagement and corruption. With the armed forces' prestige and political power at a historic low, journalists and politicians here say they now feel free to debate such issues openly after years of enforced silence.

The new furor over the disappearances has also been encouraged by the public statements of former high military government officials, who in the past have defended repression or strictly observed military vows never to discuss the issue.

"One person spoke out, and the whole building just came tumbling down," one former official said.

So far, the military man most threatened by the controversy is former Navy commander-in-chief Emilio Massera, a member of the first junta following the military coup in 1976 and one of the most powerful figures of recent Argentine history. Tall, square-jawed and outspoken, Massera was forced out of the junta in 1979 and since then has sought to win a mass following in open imitation of former populist president Juan D. Peron.

Massera and the naval security forces he managed have been linked to both the Holmberg and Sola cases by several former government officials, and human rights groups have provided the investigating courts with corroborative testimony by survivors of a clandestine prison operated during Massera's command at the Naval Mechanics School in Buenos Aires.

A former colleague of Holmberg, Gregorio Dupont, charged publicly last week that Holmberg, described as fiercely loyal to the military government, knew of a meeting in Paris between Massera and the leader of Argentina's armed left-wing Peronist faction, the Montoneros.

According to the charges made by Holmberg's colleague, other former government officials, family members and human rights groups, both Holmberg and Sola were attempting to report such activities to other government authorities at the time of their abductions. The former Argentine ambassador to Paris has also confirmed that he told the government of the alleged meetings and that Holmberg was returned to Buenos Aires from her post in Paris at the insistence of the Navy shortly before her death.

Massera has vehemently denied the charges, and his followers have begun a paid media campaign maintaining that Massera is the victim of an international campaign sponsored by the financial establishment in conjunction with terrorists.

The retired admiral's wrath has focused in particular on former military government treasury minister Juan Alemann, who touched off the public furor by saying in a newspaper interview earlier this month that the Holmberg and Sola cases were not the work of terrorists and should be investigated "in depth." Although he did not specifically blame Massera in the abductions, Alemann said he feared Massera's "micro-army" would try to kill him.

"At one time or another, this had to happen. And it is welcome," said Eugenio Holmberg, one of Elena's brothers, in an interview.

"Elena was a brave woman, and because it was known she had certain information and was passing information, they killed her," he said. "We think what is happening now will serve to bring the delinquents who killed her to justice."