The government of President Raul Alfonsin has uncovered a network of heavily armed, right-wing terrorists that is believed to have carried out bombings and abductions in an effort to destabilize the country's 18-month-old democracy, officials here said.

The discovery of the group this week and a raid on its secret arsenal represented the first time that authorities have taken successful measures against a right-wing paramilitary organization since such activity first began to flourish in Argentina 15 years ago, officials said.

Although most of the alleged members of the terrorist group remain at large, several Argentine commentators said the most important aspect of the case had been the evident willingness of the police to crack down on paramilitary activities for the first time.

"For the last decade or so Argentina has been a kind of paradise for right-wing terrorists," said an editorial in the Buenos Aires Herald. "The mere fact that police have managed to swoop on what is clearly an important, well-armed and well-organized gang suggests that something very significant is happening in Argentina."

The new evidence of rightist violence supported assertions by human rights groups and some government officials that paramilitary groups dating from the era of the military's rule and bloody "dirty war" against leftists continue to operate on a significant scale in Argentina.

"Terrorism of the right has had access to all the resources, and only now are we beginning to apply justice to it," Interior Minister Antonio Troccoli testified before Congress. "We have been able to identify two right-wing cells, and they represent the tip of the iceberg."

In a series of raids during the past week, police discovered an extensive cache of arms, documents and electronic equipment and arrested three persons tied to what was described as a 15-member cell of terrorists.

Interior Ministry Undersecretary Raul Galvan said the band was made up of former agents from military security and intelligence services and that several members also were linked to a notorious terrorist organization of the 1970s -- the Argentine Anti-Communist Alliance.

The accused leader of the band, Raul Antonio Guglialminetti, is a former security and intelligence agent attached to the government palace who continued in official service even during the first three months of Alfonsin's government, officials said.

Guglialminetti, who also reportedly served as a trainer to Nicaraguan antigovernment rebels in Honduras, is now a fugitive.

A search of Guglialminetti's two homes and five other properties of the group uncovered a number of weapons and military uniforms as well as high explosives, sophisticated radio transmitting equipment and a rocket whose warhead contained napalm, police said.

In a press conference this week, Galvan said that the group appeared to be operating with other right-wing cells still not identified by police in a concerted effort to destabilize the government during the ongoing trial of nine former military commanders on human rights charges.

The rightists had been linked to robberies of arsenals, kidnapings, cases of extortion, and several recent bombings, Galvan and police officials said.

"These groups acted under military authoritarianism," Galvan said. "They did not spontaneously come into existence and their activities are directly linked to the trial of the military juntas."

Paramilitary activity has been persistent throughout Alfonsin's government, despite efforts by authorities to bring military intelligence and government security services under control.

More than 40 bombings and 18 abductions were reported around Argentina during 1984.

Most were directed against human rights organizations, social workers and left-wing activists and were attributed by the government to "unemployed manpower" from the military era.

As the human rights trial of the military began last month, a new wave of violence was reported, including the bombing of a local radio station and the beating of several prospective witnesses.

The police crackdown, however, appeared to have been triggered by the kidnaping of a prominent industrialist, Enrique Pescarmona. Pescarmona was held for 42 days before being released last week after a reported ransom payment.

Shortly after the industrialist's release, police began raiding homes apparently linked to the kidnaping. The searches turned up evidence linking the Guglialminetti group to the bombing of the radio station as well as two other kidnapings, one of which ended with the slaying of the hostage, authorities said.