President Fidel Castro has enhanced his image on human rights by releasing hundreds of political prisoners, but dissidents say thousands more remain in jail or are ostracized for opposing the regime. Communist authorities have nearly halved the dissident population in Cuban prisons since Cardinal John O'Connor of New York asked Castro to release 433 people charged with political crimes, said Bienvenido Avierno, a Foreign Ministry official. O'Connor visited Cuba in April. Former political prisoners are among the 300 or so Cubans leaving Havana each month aboard charter flights that depart four times a week for Miami. Asked if the releases benefit the government by letting it purge dissidents, Avierno said, ``Sure, we are maintaining these guys.'' One dissident here says the government has only become more sophisticated in curbing its domestic opposition. ``Everything is repressive here,'' Ricardo Bofill, president of the banned Cuban Human Rights Committee, said in a recent interview at his one-room apartment in the Havana suburb of Guanabacoa. ``Their tactics have changed. Now they use mobs and press campaigns.'' Bofill, a Communist Party member before Castro came to power in 1959, has been jailed several times for speaking out against the government. He has stayed at home for the past four months, saying he fears for his life. ``There are death threats. I have been identified in Cuba as the head of the counterrevolutionaries, the No. 1 enemy,'' Bofill said, sitting in a rocking chair in his room. The Communist Party newspaper Granma devoted several pages in April to discrediting Bofill. ``He is totally twisted and imbued with double-dealing lies, faking, deception and, especially a monstrous ego and unquenchable thirst for fame and notoriety,'' it said. Bofill's group compiles and distributes reports of government abuses. He showed a reporter a handwritten prison pamphlet called ``Dawn,'' which detailed ``systematic cruelty.'' He said Cuba has 10,000 political prisoners. Amnesty International, the London-based human rights group, put the number at 450 in its 1987 annual report. The Castro government tolerates Bofill, often citing his criticisms as proof Cuba has freedom of expression. Avierno flatly denies there are any rights abuses in Cuba: ``The people, for the first time in their lives, have the arms. If they didn't like the system they could use them.'' Bofill said he does not oppose the government, but rather its tactics: ``This is not a fight against the system, it is against an unjust order. The basic rights, the right to life, is not guaranteed.'' In Cuba, only state-run news media are allowed to operate and the government decides who can leave the country and who can return. Bofill displayed his identification card, a booklet resembling a passport, and showed the government stamp that indicates he has applied for permission to leave the country. He said the stamp identifies him and thousands of others as malcontents. Roberto Bermudez, 32, a painter, said his opposition to the government has meant he can't exhibit his paintings. Sebastian Arcos, a former professor of dentistry and ex-political prisoner, said thousands of Cubans depicted as social outcasts are unable to find work. Cuba's socialist policies mean free and often model health care and education. The government says its provision of these social services constitutes a human right. ``This is a country where we have education, health, a country where drugs, especially hard drugs, are unheard of. No child needs to leave his studies to help his family. Violence is practically unknown. These are human rights,'' Jose Ramon Fernandez, vice president of the Council of State, said in an interview. Castro this year permitted the International Red Cross to examine Cuban prisons for the first time. A confidential report is being prepared. In addition, a United Nations human rights group is expected to inspect the prisons by September. The United States maintains no formal diplomatic relations with Cuba. But the U.S. Interests Section in Havana receives ``thousands upon thousands of letters from Cubans requesting political asylum in the United States,'' spokeman Jerry Scott said. An agreement renewed last year will allow 3,000 Cubans to travel to the United States as refugees. Avierno said the Cuban government agreed to free most of the prisoners requested by O'Connor ``if the United States guarantees they can go there.'' About 40 of that group will not be released because they ``are very dangerous people and they must fulfill their sentences,'' Avierno said. The maximum prison term is 30 years.