The nine-member Armed Forces Supreme Council, Argentina's highest military tribunal, resigned en masse today, washing its hands of hundreds of human rights cases, including those against former top military men accused of mass murder.

The move presented the 11-month-old democratically elected government of President Raul Alfonsin with a dramatic challenge as it sought a last-minute reversal of the council's decision in order to keep the cases in military courts.

The government has relied heavily on the armed forces to conduct its own housecleaning of those who committed illegal arrests, torture and murders during nearly eight years of military rule.

Today's decision appeared to end official hopes that the armed forces would take steps to distance themselves from the personal plight of their former leaders. While Alfonsin could appoint another military tribunal, most observers say they expect that more than 600 rights cases now before the council will be transferred back to civilian courts.

"Today's action only confirmed what we already knew -- the Supreme Council does not want to judge its peers," said Emilio Mignone, a lawyer and human rights activist.

"This is proof the government's policy of having the military judge themselves is a failure," he added. "I think we'll be seeing trials for some time to come."

Alfonsin, in one of his first acts upon taking office, ordered the courts-martial of the nine members of the first three military juntas, which ruled Argentina from 1976 to 1981, for massive rights violations, including mass murder.

The charges stem from a military-led "dirty war" conducted against leftist guerrillas and suspected sympathizers during the mid- to late 1970s. During that time more than 8,000 people disappeared and most are believed to have been killed by government security forces.

In a highly controversial move early this year, Alfonsin forced a law through Congress that allowed the rights cases to be removed from the civilian courts to the military tribunal, with a later review by a civilian appeals court.

Until last month the Supreme Council had been charged with trying the members of the first three juntas, whom Alfonsin had accused of being responsible for the kidnaping, torture and deaths of thousands of Argentines.

Shortly after the council ruled that the orders issued by the juntas for carrying out the antiguerrilla fight were "unobjectionable," a federal appeals court removed the cases from the military's jurisdiction.