Progress on prison sieges as Cubans mull US offer. LOUISIANA HOSTAGES FREE

The Cuban detainees have made their case to the public, and clearly improved the chances of many of them to stay in the United States. But the longer the hostages are held - well over 80 at Atlanta and Oakdale, La. - the more the rebellious inmates risk losing whatever public sympathy they have gained, says lawyer Gary Leshaw, a longtime advocate for the Cubans.

By press time Sunday, inmates at Oakdale released most of the 26 hostages they had been holding.

Before the rioting began in Oakdale and Atlanta a week ago, even avidly anti-Castro Cuban exiles had few qualms about deporting the ``excludable'' Mariel refugees back to Cuba. That's changing.

After years of little widespread attention or concern, the cause of fair hearings for each of the detainees attracted virtually universal support among politicians.

``The thing that really galls me is that all these people are suddenly concerned,'' says Mr. Leshaw, a longtime advocate of more thorough hearings for the detainees. ``The question is, where have these people been? It's been going on for seven years.''

After near resolution of the siege at Oakdale on Friday, the atmosphere grew more highly charged at both prisons over the weekend.

On Saturday, the government began drawing a tougher line and introduced a time element into the negotiations. United States Sen. John Breaux (D) of Louisiana, who is observing negotiations at Oakdale, announced that the government would not make further compromises. Also, federal officials cut off the water and heat to the Atlanta prison.

The inmates at Atlanta reacted angrily, setting new fires. But by Sunday morning, they abruptly decided to release four hostages, who said they had been treated well.

Both besieged prisons are thought to have weeks of food supplies. Officials are uncertain how long water supplies will hold out in Atlanta.

Inmates have complained throughout the past week that they do not trust the Justice Department. At the same time, the federal negotiators have blocked the participation of a steady stream of outsiders who either request to play a role or are sought by the inmates.

In defense of its refusal to permit outsiders to participate, the Justice Department cites both a need for the government to speak with one consistent voice and the possibility that prisoners will continue to demand new negotiators.

The basic offer of the government, announced early last week by Attorney General Edwin Meese III, is to delay all deportations until each detainee's case is individually reviewed on its merits.

A few days later, federal officials said that Cuban exiles, including Roman Catholic Bishop Agustin Roman of Miami, would have a voice in designing the hearing process.

Bishop Roman arrived at Oakdale on Saturday. Banners flown by the inmates claimed they would sign an agreement only after it had been approved and signed by Bishop Roman, who has been a longtime advocate of the detainees' rights.

Yesterday the Oakdale inmates were shown a videotaped message from Bishop Roman urging release of the 26 hostages there. The hostage release followed the bishop's appeal.

If Oakdale inmates arrive at an agreement, says attorney Leshaw, ``it would go a long way in Atlanta.''

Some advocates for the Cubans' rights are disturbed at being shut out of the conflict. US Rep. John Lewis (D) of Atlanta, for instance, has been requested at negotiations by the inmates, since he has been promoting thorough individual hearings for them for at least six months.

Says an aide to Congressman Lewis: ``The people that the inmates trust the most have not been allowed to participate.''

At Oakdale, negotiations have been kept extremely private by Justice Department officials, although Senator Breaux has observed some of them. In Atlanta, negotiators have allowed observation by lawyers trusted by the inmates, such as Leshaw; two former political prisoners in Cuba, Armando Valladares and Roberto Martin Perez; and Jorge Mas Canosa, a Cuban exile leader and lobbyist.

At this time, Leshaw believes that the inmates should trust Mr. Meese's promise of hearings. Even if the administration were to try to renege, he says, ``I think we [advocates] have some credibility now. It would be harder to ignore us.''

A week ago Friday, the day the deportation agreement with Cuba was announced, Immigration and Naturalization Service officials said they planned to begin deporting Cuban excludables as soon as possible. No further hearings were planned for the 2,545 Cubans to be accepted by Cuba under the agreement.

It is less clear how many more Cubans the US would attempt to deport. In addition to 3,800 Cubans in detention now, almost 4,000 more are headed for detention after serving prison sentences.