Through three days of briefings about rioting Cuban inmates facing possible deportation, Justice Department officials have sidestepped the question of whether government officials had enough warning and took adequate measures to prevent the outbursts. The time for "post-mortems" will come later, the officials said, once the situation has calmed.

But Bureau of Prisons Director J. Michael Quinlan, pressed yesterday to say whether the riots at federal facilities in Atlanta and Oakdale, La., could have been prevented, finally offered his perspective on the riots.

"In my own judgment, I don't think it could have been avoided," said Quinlan, pointing to the unique nature of the revolt, which was triggered not by overcrowded conditions or mistreatment of inmates but by an announcement from the State Department.

"In the history of corrections, I don't think there's ever been a situation ignited in a prison external to the condition in the prison itself," Quinlan said. "This is the first in corrections history."

Justice Department officials complained privately, however, that the State Department left them with little time to try to prevent the outbursts, sparked by the announcement that Cuba had agreed to reinstate a 1984 pact to allow the return of "Marielitos" -- Cubans who came to the United States in the 1980 Mariel boatlifts to Florida -- found ineligible to remain here.

Attorney General Edwin Meese III said Monday that he received a telephone call informing him of the agreement at 7 a.m. Friday -- five hours before the State Department made its public announcement. Justice Department spokesman Patrick S. Korten said yesterday that "no one {at the Justice Department} was aware of it before Thursday evening at the earliest. It is probably the case that it was Friday morning before any of us knew" that Cuba had agreed to accept the return of 2,746 "excludable" Cubans.

J.R. Johnson, warden of the Oakdale detention center where the riots first began Saturday night, said Tuesday that he had only an hour's warning of the announcement. "There was a definite problem in the late notification, and, really, the way it was distributed," he said. "My detainees all thought they were going to be one of" those returned to Cuba.

Justice Department officials said they tried to take precautions once they heard about the reinstatement of the agreement with Cuba. "We anticipated that there might be some problems, and for that reason we put additional staff in the institutions where we had Cuban Marielitos housed," Quinlan said.

He said the prison staffs were told "to be on the lookout for particular signs that there might be problems. They reported none. Up till the very moment before the Oakdale disturbance, there were no reports of any potential anxieties or threats," he added. "We should have had more time . . . . We thought we were on top of it. Obviously there were some plans or some leaders in the groups who had other plans, and we were not privy to them."

Those at the scene, however, told a different story. Teresa Cordero said her husband called her Friday night from Oakdale and told her that the prisoners had seen several Immigration and Naturalization Service buses drive up to the prison entrance that day, prompting them to speculate they were about to be deported.

Initial signs of trouble in the Atlanta federal penitentiary also came Friday with a work stoppage in the prison as word of the revived deportation agreement spread. "A lot of Cubans were confused and upset," said Warden Joseph Petrovsky, who sent staff members to try to calm them.

"We told them we felt it would affect very few of them and asked for their patience and understanding. We told them that, as we got information, we would pass it on."

By Saturday, he said, "things were normal . . . . Had I locked down the institution, it would have blown up immediately. Then people would be asking me today, 'Why did I lock it down when the . . . atmosphere was so good?' "

Korten noted that a "lock-down" at the penitentiary in 1984 sparked a riot, with mattresses burned and windows broken. "You have to make a judgment," he said. "They concluded that a lock-down was not worth the risk." In addition, he said, there were no similar outbursts when the pact with Cuba was first reached three years ago. "It was reasonable to assume that since we were picking up with a program already in operation there was not this kind of risk of an outbreak," he said.

But lawyers who have represented the Marielitos said the riots could have been predicted. Courts have ruled that the Cubans, although they have been in the United States for seven years, are legally considered never to have entered the country -- and therefore do not have the constitutional rights afforded other aliens.

"These people have good reason to be suspicious about what's going to happen to them," said Gene Guerrero, executive director of the Georgia American Civil Liberties Union.

As a result of court rulings restricting their rights, Cubans who have served time for crimes have been detained indefinitely, awaiting their eventual expulsion from the United States. In June, with Cubans crowding federal facilities, the INS announced a plan to review detainees' cases and send those who could safely be released to halfway houses or their families -- the first good news many of the Marielitos have had in years. Friday's announcement threatened to end their hopes of freedom in the United States.

"It was astoundingly poor planning on the part of the government officials," said Arthur C. Helton, director of the Political Asylum Project of the Lawyers Committee for Human Rights. "Take a population indefinitely detained, raise their expectations dramatically, then dash them with this announcement, then leave ambiguous who's at risk and who's not -- it's a prescription for these disturbances."