A processing center for Cuban refugees will be set up at Eglin Air Force Base in Florida in an attempt to control the continuing flood of the world's newest boat people, federal officials said yesterday.

The base, near Pensacola in the Florida panhandle, was used as a processing center for Vietnamese refugees in 1975. The Cubans will be airlifted to Eglin from Key West, officials said.

Reports arriving in Washington from Havana and Key West yesterday made it clear that the extent to which Cuban President Fidel Castro has been "emptying his jails" is becoming an increasingly important element in the handling of the refugees.

Washington Post special correspondent Marlise Simons reported from Havana that the Cuban government appeared to be giving earlier preference in departure papers to those who had served jail terms than to those who took refuge in the Peruvian Embassy a month ago.

New offices reportedly have been set up in Havana neighborhoods to expedite the departure of people with criminal records, and several persons reported that police had gone to the homes of relatives released from jail to offer them exit documents.

In Key West, meanwhile, many of the boats arriving from Cuba yesterday carried such "criminals." Many of those interviewed said they had been jailed for political crimes, such as trying to escape to the United States.

About 60 of the refugees -- of 7,200 processed so far -- have been detained at the Federal Correctional Institute in South Miami because of suspected criminal records.

Carter administration officials in Washington regarded with caution reports of Castro "emptying the jails," noting that Cubans can be imprisoned for acts that wouldn't be considered crimes here, such as failing to meet a factory quota.

About 3,000 boats are in the Cuban port of Mariel, waiting to pick up relatives, while more are speeding toward Cuba every day, a U.S. Coast Guard spokesman in Key West said.

Three large boats -- the Ocean Queen with 103 refugees, the Viking Starship with 500, and the Hunter with more than 200 -- arrived without a single relative of the Cuban Americans who had hired them. The Queen and Hunter disgorged sullen-looking young adult males -- in sharp contrast to earlier refugee boats with women, children and grandparents.

Several small craft, however, landed in Key West half full of relatives and half full of refugees who had sought asylum in the Peruvian Embassy in Havana.

Refugees interviewed at dockside said that thousands of Cuban prisoners were being held at an enclosure in Mariel, apart from the families whose American relatives were in the harbor and apart from the Peruvian Embassy refugees.

The prisoners were mixed into each departing boatload after being handed papers falsely identifying them as Peruvian Embassy refugees, according to newly arrived Cubans.

Francisco Fuentes, 24, standing under a burning Key West sun as he waited for the bus to Miami, held up his Cuban visa and proclaimed, "This says I was in the Peruvian Embassy. But that is a lie. Now I'm in a free country so I will tell the truth."

Fuentes said he was fetched from his home by Cuban police and told to leave for Florida or go to jail. "I am a dissident from the system. I would not belong to the Union de Juventud or the Committee for the Defense of the Revolution, so they fired me from my job. They wanted me to go to the countryside and cut sugar cane. I said no. So I was sent to prison for eight months in 1974."

Fuentes, who served three years in the military after his prison term, said he was forced to leave his wife and three children in Cuba. "In a few years I'll get them out. You have to have faith."

Another refugee, Luis Morales Suarez, said that while many prisoners in the Mariel compound were common criminals, "You can get 20 years for stealing a bottle of rum.Many people are in prison for taking a few beans to feed their families."

Maria Antonia Espinosa, a 96-year-old grandmother in a wheelchair, arrived on her grandson's boat. "For many years I've been praying to come here," she said, clutching a large crucifix. In Cuba, she said, "if there is sugar, there is no coffee. If there is coffee, there is no cup."

Other refugees from Mariel said the old woman had suffered heroically during days without food. Finally, she tore open her shirt, bared her breast to the guards and said, "Either you get me out of here or you kill me." b

Leoncio Estabez, 49, a frail-looking man with dark glasses, said he served five years of a 15-year sentence for "trying to leave by boat in 1966 and for criticizing the revolution."

Estabez sought refuge in the Peruvian Embassy along with 10,800 other Cubans. "I had to leave my wife and children," he said sadly. "They were afraid to go into the embassy. But I felt even if I died doing it, I had to get out."

So far, Cubans have been processed briefly in Key West and then been bused to Miami for further interviews at a Dade County park. There they are given asylum applications and told to report back to the Immigration and Naturalization Service in 60 days.

When the center at Eglin is set up, those refugees who don't have relatives in the Miami area will be flown to the air base for complete processing. Dewey Knight, assistant Dade County manager, said in a phone interview yesterday that the federal government had agreed to reimburse Dade for its expenses.

Cuban community groups have borne much of the expense so far, providing clothing, food and even money for their countrymen, Knight said.

One federal official said the refugees arriving at Eglin will be housed temporarily in tents, but there are no plans now for long-term stays there.Again the Cuban community groups are being counted on to help find homes and jobs for the newcomers, he said.

An Air Force officer at Eglin said a survey team estimated that the facility could handle 15,000 refugees.

Part of the goal of using Eglin is to regularize the process, in hopes that Castro eventually will agree to a more orderly departure for the refugees than the dangerous trip in small boats, officials said.

Sen. Edward M. Kennedy (D-Mass.) took time out from his presidential campaign yesterday to issue a statement calling for diplomatic contacts with Castro "to help bring some order to the current exodus of Cubans." State Department officials said there have been no discussions with Castro. "There are no grounds to negotiate with him," one said.