By MARC LACEY

MEXICO CITY — The Cuban government’s announcement last week that it will release 52 political prisoners has done little to quell the island’s fiercest critics, who are asking President Raúl Castro, “What about the rest?”

But exactly how many people are said to remain jailed on the island because of their political beliefs varies widely, depending on who is doing the counting. On the low side, Amnesty International says that only one confirmed prisoner of conscience will remain in Cuba should the Castro government follow through on its plans to release all 52 in the coming months. That one prisoner is the lawyer Rolando Jiménez Posada, and the human rights group — which coined the term prisoner of conscience in the 1960s — called on Cuba to immediately release him as well.

Before the announcement of the latest planned release, the Cuban Commission on Human Rights, an independent group that is tolerated on the island but not recognized by the government, put the number of political prisoners at 167, which it said was the lowest since the 1959 revolution in which Fidel Castro came to power. Its new figure, should all 52 get out, will be 115.

Other groups, however, say the real figure is much higher. Human Rights Watch does not specify an exact number, but includes in its tally scores of people who have been arrested in recent years for the vague Cuban crime of “dangerousness."

Some former prisoners contend that there is a political element to so many detentions in Cuba — and that the government does not allow adequate legal representation to those it wants isolated. They say the real number probably reaches into the thousands.

“If the Castro tyranny really would like to make a good faith gesture, it ought to liberate all those prisoners in its dungeons,” said Miguel Sigler Amaya, an activist now based in Miami who spent two years in a Cuban prison for “disobedience” and “resistance,” and contends that thousands of fellow Cubans are detained on similarly nebulous charges. One of his brothers, Ariel, a political prisoner, was released last month after suffering health problems in prison, and another, Guido, is among those expected to be released.

The brothers were among the activists and journalists rounded up by the government in March 2003 in a mass crackdown on dissent known as Black Spring. Those detainees were arrested on various charges and convicted after brief, closed trials. Their sentences ranged from six years to 28 years.

For its part, the Cuban government puts the number of political prisoners that it is holding at zero. Fidel Castro, the ailing former president, acknowledged holding thousands of prisoners of conscience decades ago, but in recent years he has said that Cuban jails hold only common criminals and those who illegally acted as paid agents of the United States.

One reason for the varying figures is the definition of who, exactly, is a political prisoner. Another is that the Cuban government has not allowed the International Committee of the Red Cross to visit its prisons.

Agreement on a precise figure is unlikely, as is determining why President Castro chose to make his drastic announcement now. Another looming question is how the United States, which has long called for the release of Cuba’s political prisoners and has welcomed those released in the past, will respond to President Castro’s overture.

“It’s something that is overdue but nevertheless very welcome.” Secretary of State Hillary Rodham Clinton told reporters last week.

Acknowledging that its figure is on the low side, Amnesty International defines prisoners of conscience as those inmates jailed for their beliefs who have been found not to have used or advocated violence.

“Some other ones may not be on our radar,” said a spokeswoman for the group, Guadalupe Marengo, who noted that Amnesty had not been permitted to visit Cuba to conduct research in more than two decades.

Amnesty International said Mr. Posada, the one remaining Cuban inmate it considers a prisoner of conscience and thus entitled to immediate release, was given a 12-year sentence in 2003 for “disrespecting authority and revealing secrets about state security police,” after he participated in a peaceful demonstration calling attention to the plight of political prisoners.

Human Rights Watch, which conducted a surreptitious study inside Cuba last year, documented more than 40 cases of people imprisoned for “dangerousness” since Raúl Castro replaced his brother in 2006, as well as scores of other people sentenced for violating laws that criminalize free expression and association.

Noting that Cuba has conducted prisoner releases in the past and then gone on to fill its jails with even more political dissidents, Human Rights Watch said that the country’s judicial system clearly needed an overhaul.

“The international community needs to pressure Cuba to go beyond the periodic release of jailed dissidents and instead dismantle the repressive laws, courts and security forces that put them in prison in the first place,” said José Miguel Vivanco, Americas director at Human Rights Watch, who secured the release of six prisoners from Cuba in 1995.

One aspect of the planned release that has critics of the Cuban government upset are reports that once the prisoners are liberated, they are to be flown out of the country, and thus will be far less able to continue their activism and hold the government accountable.


But Cardinal Jaime Ortega, Havana’s Roman Catholic archbishop, who played a critical role in negotiating the releases, suggested that leaving Cuba would be an option, not a requirement, for the former prisoners. The first 17 are expected to travel to Spain as early as Monday, church officials said. Others may choose other countries or decide to stay in Cuba, they said.

The decision, which was first reported by the Roman Catholic Church but later appeared in the Communist Party newspaper Granma, although with no mention that the inmates to be released were political prisoners, prompted the activist Guillermo Fariñas to end the hunger strike he had begun in February to press the government to release ailing prisoners.

But Mr. Fariñas would not take credit for the planned release. A statement that his supporters pressed up to a window in the hospital where he remained Sunday said, “Only Cuba, our nation, has won.”

Antonio Betancourt contributed reporting.