Forty-four of the 126,000 Cubans who sought asylum in the U.S. aboard the "Freedom Flotilla" remain confined 18 months later behind barbed-wire fences at St. Elizabeths Hospital in Southeast Washington.

While most Cubans in the massive exodus have been eased into jobs, homes, schools and other facets of American society, this small group is part of the 450 in psychiatric facilities around the country out of about 4,000 entrants still in custody of the Immigration and Naturalization Service, according to Dr. Larry Silver, deputy director of the National Institute of Mental Health.

Legally they are not in the U.S., and although they occupy a 19th century St. Elizabeths building outfitted with special security equipment and patrols, they technically are not in the hospital.

Federal agencies have cared for the Cubans in "a very difficult situation over the past year," Silver said, at a cost of "millions of dollars." Some services have been purchased from private contractors at twice the amount it would cost the government to provide them directly, but the government does not have the staff to do the work.

Immigration laws provide for deportation of aliens who have been identified as mentally ill, retarded, criminals or dangerous to themselves or others, but because Cuban Premier Fidel Castro "refused to take them back," the Cubans in psychiatric programs are "constantly in a dilemma," Silver said.

Consequently, St. Elizabeths' Building B has become a prison. It has been home to a fluctuating group of 20 to 80 Cubans since last October and from which some have been placed in the community, only to be sent back for bad behavior.

"To INS they still are potentially illegal aliens and potentially excludable and as a result the facility is directed by INS as a detention facility; decisions are based on security rather than psychiatric care," Silver said.

Richard Boswell, director of the Immigration Law Clinic at George Washington University Law School, said conditions inside Building B are "regimented" at best. " In the view of the six or eight clients we've had there, their movements are almost totally restricted. They are confined to their wards and allowed a couple of hours a day to walk around outside."

Boswell said the Cubans are allowed to make telephone calls only to Cuba, and that last summer was especially difficult for them because Building B is not air conditioned.

"They have some kind of language training and can watch TV at certain hours. For a number of them, because they have this indefinite feeling that they don't know when they can get out, they often rebel and they are given drugs," Boswell said.

The inmates of Building B can lose the privilege of taking walks outside and receiving snacks or cigarettes for such misbehavior as fighting or making noise, according to a memorandum in Spanish issued last month by director of nursing Ann Bucher.

"Now, if you the residents believe that these rules are too strong, we can make them stronger . . . Until you change your negative attitudes, there will not exist the slightest chance of leaving here," the communique warned.

Boswell, attorney for two twice-returned inmates, men 17- and 28-years-old, sought unsuccessfully last week to secure their release in a petition filed in federal court here.

Housed in the midst of the huge federal mental hospital, they are provided mental health evaluation and treatment under an NIMH contract with Preventive Health Services, a private Falls Church firm.

Most of the men, who are 18 to 60 years old, have "very long histories of psychiatric disabilities in Cuba, but not all of them," according to Ann Marshall, a psychiatrist in the Cuban-Haitian Mental Health Unit at NIMH. They have low-level academic records and speak almost no English, Marshall said.

"Castro just swept the streets of Havana and sent us all the undesirables," Silver said. He said most of the Cubans here were prisoners, the unemployed and the poorly educated.

"It's a combination of detention and services for mental illness. Some have severe chronic mental illness and others are just vulnerable to stress," said Marshall, who is in charge of resettlement for the mental patients. Some, after being released to community homes, have been returned when they have been unable to adjust to the outside world, she said.

INS has spent close to $6 million on the Preventive Health Services contract in the past year for evaluation and treatment services. In addition, border patrol officers and security patrols guard the Cubans, St. Elizabeths provides linen and housekeeping and the U.S. Public Health Service gives them medical care.

For an average cost of $1,751 a day, a food service contractor trucks in three meals and two snacks a day of foods preferred by the Cubans: chicken and rice, red beans and rice, fried plantains, shrimp creole, barbecued ribs and expresso coffee, according to Arthur McZier, president of the firm, National Business Services Enterprises. Silver said the food could have been provided by St. Elizabeths at about half the cost, but the hospital did not have the staff to do so.

McZier rents space in the Last Hurrah restaurant, at 22nd and P streets NW, and employs two Cuban cooks and helpers to prepare the meals.

Another 100 Cubans with psychiatric problems are housed in a similar program at Fort Smith, Ark., 100 more have been identified in Atlanta Federal Prison as needing such care and about 100 others are in private, nonprofit halfway houses and other programs around the country under federal contracts, Silver said.

Building B is scheduled to be returned to St. Elizabeths' control at the end of January, by which time NIMH hopes to have placed most of the Cubans in state or private facilities at federal expense, but such placements must be voluntary, and those who refuse will remain federal wards, Silver said.