ATLANTA, DEC. 2 (WEDNESDAY) -- After a 45-minute negotiating session that ended early this morning, a lawyer allowed in to advise the Cuban inmates, who had released another hostage at 9 p.m. Tuesday, emerged from the prison here to announce that the Cubans and the government are "very close" on all but "a couple of hard points" to a resolution of the 10-day siege.

"A lot of things have been settled," Gary Leshaw, a lawyer for the Coalition to Support Cuban Detainees, said on leaving the prison early today. "We need to get some answers . . . on what can and cannot be done," said Leshaw, who announced that he expected to return to the prison before noon today to continue negotiations.

Tuesday night, the inmates released a hostage after announcing from the prison roof that the release was in honor of the 29th birthday of a woman who has worked on their behalf for two years.

Justice Department officials said that as a quid pro quo for the hostage release, they had agreed to accept Leshaw as a legal adviser to the negotiators.

More than 100 detainees crowded the roof under a cold night sky to sing in English "Happy Birthday" to Carla Dudeck, coordinator of the Coalition to Support Cuban Detainees. Over the past two years, she has written hundreds of letters to the inmates as the coalition's lawyers provided legal assistance. She stood across the street waving.

A voice among the singing, cheering inmates then announced that they were releasing a hostage in her honor, and "Carla, you can go pick up your hostage." She said she went to the prison gate and told astonished FBI agents, "I'm here to pick up my hostage."

An Atlanta policeman escorted her to the prison gate, but she was abruptly turned back by an official who, she said, told her, "We don't negotiate the release of hostages in this manner, and no comment."

Justice Department spokesman Patrick S. Korten confirmed that a hostage had been released, and identified him as Abdul-Saboor Rushdan, 36, a senior corrections officer at the facility since 1984. He is married and has a son and daughter. Rushdan emerged from captivity wearing a cap and an olive-colored vest and was expected to be taken to a hospital for a checkup.

Justice officials attempted to play down the relevance of Dudeck's birthday. Korten said, "I really don't know anything about the birthday issue," and another official said federal negotiators had never heard of her.

Rejoined Dudeck, "All I can say is what I heard them say over the loudspeaker: that they're releasing him for me."

The release, which left 89 hostages still inside the prison, also came shortly after Leshaw asked the hostages in a Spanish-language broadcast to do so in Dudeck's honor and to give him legitimacy as a negotiator. Korten said Leshaw was allowed inside the prison to serve as a legal adviser to the detainees negotiating for the 1,108 who remain inside.

In an earlier loudspeaker broadcast from the prison roof, a man identifying himself as a representative of the "Executive Committee of Atlanta Detainees" said the entire Cuban population inside the prison had determined that the agreement that ended a similar siege in Oakdale, La., "has its shortcomings" and does not appear to be legal. However, the unidentified man, speaking as more than 100 detainees crowded the roof, said that a counterproposal will be offered and "we are confident that very soon this crisis will end."

He said the Oakdale agreement shows that Cubans had been "cheated and deprived of their rights once again" and that "the government duped our Cuban brothers in Louisiana."

Earlier Tuesday, several FBI negotiators and four representatives of Cuban inmates reached "substantial agreement on a number of issues" during a businesslike and "courteous" session, Korten said.

But he added that difficult issues, which he refused to specify, have not been discussed, and that it is uncertain whether the detainees will accept the tentative agreements.

No members of the radical group that authorities have blamed for blocking a settlement were involved in Tuesday's negotiating session.

Despite his cautious language, Korten said that the negotiating session at 12:30 p.m. Tuesday "was considerably more encouraging than others we have had in the past few days."

Korten refused to discuss the "core issues," but the inmates are understood to be demanding U.S. citizenship, no reprisals and the right to go to a third country, rather than Cuba, if they are deported. The uprisings in Oakdale and here were sparked by an agreement with Cuba to return up to 2,500 of the thousands of Cubans who came to the United States in the 1980 Mariel boatlift. Many of those destined to return were being held at the two facilities.

Federal authorities are trying to persuade the detainees to accept the Oakdale provisions, which essentially promise fair hearings and no reprisals.

Authorities said today that when an agreement with the Atlanta inmates is near, they would seek the participation of Auxiliary Bishop Agustin A. Roman of the archdiocese of Miami, whose presence at Oakdale led to a settlement there. Korten said Roman, who remained in Florida Tuesday, has emphasized that he does not want to be a negotiator, but would be available to help persuade the inmates to accept a settlement.