To cheers from a packed courtroom audience, federal prosecutor Julio Strassera asked for life imprisonment for five of the nine former military commanders on trial here for murder, torture, enslavement and kidnaping in the so-called "dirty war" against leftist guerrillas and their sympathizers.

Strassera ended six days of often tedious oral summation in the trial of Argentina's once powerful military leaders with a ringing oath that brought the audience to its feet.

"Your honors," Strassera said. "I wish to use a phrase that does not belong to me, but rather to the Argentine people.

"Your honors: Never again!"

In the ensuing pandemonium, Judge Leon Arslanian ordered the courtroom cleared. As the defendants got up to leave, cries of "murderers" from the balconies caused one former military president, retired general Jorge R. Videla, whom Strassera had called one of the "principal architects" of the repression, to stare uncomprehendingly at his accusers. Retired general Roberto Viola, who succeeded Videla as president, was clearly rattled by the disturbances, and began to curse over the din.

The emotional finale to Strassera's presentation saw the prosecutor ask for life terms for Videla and Viola, retired admirals Emilio Massera and Armando Lambruschini and retired Air Force brigadier Orlando Agosti.

Strassera also asked for penalties of between 10 and 15 years for the four other defendants, including a 15-year sentence for former president, retired general Leopoldo Galtieri.

The nine officers are charged with responsibility for hundreds of kidnapings, murders, tortures and robberies committed by successive juntas between 1976 and 1982 during their battle against leftist guerrillas and other dissidents.

The defense, which is scheduled to begin its summation Sept. 27, is expected to argue that the military rulers were unaware of abuses committed by their subordinates. A verdict is expected by December.

In his remarks today, Strassera ridiculed the notion that the antiterrorist fight, which reached its peak in the mid-1970s, resembled a war, as the ruling generals had said.

Noting that thousands of people disappeared after being abducted during the military regime, Strassera pointed out that the generals at first had denied what was happening. It was only later, he said, that the military began to offer "undeclared war" as an explanation.

"What kind of war was this?" he asked mockingly, "where different operations were not documented, where no battle instructions were issued nor lists of enemy or friendly casualties, nor those of the wounded, where no prisoners were taken and in which it is unknown which units took part?"

Strassera charged that the methods used by the military violated national and international norms, such as the Geneva Conventions.

For the first time since the public trial began in April, the six-man federal court panel required the defendants to appear at the downtown court building when arguments began last week.

In opening remarks last Wednesday, Strassera accused the nine of having taken power "by assault" in overthrowing the previous elected government, and having responded to a challenge by leftist guerrilla groups with a "fierce, clandestine and cowardly" repression "that produced the same evil they said they were combatting."

As the summation unfolded, the defendants appeared nervous and uncomfortable.

Former president Galtieri, who was a picture of confidence while in office, has chain-smoked throughout the proceedings, shifting his bulky body in his chair and constantly moving his legs.

Videla spent a good deal of the sessions reading religious tracts, looking up occasionally to stare at a cross behind the judge's bench. Viola, who the prosecution expects will present the most spirited defense, has been taking copious notes.

Yesterday, the prosecution presented what it called "the legal grounds that cause us to ask for convictions," after having spent the previous four days reviewing the 709 cases of rights violations used during the trial against the military men. More than 9,000 persons disappeared and are believed to have died after being abducted during the "dirty war."