President Fidel Castro played congenial host today to heads of state and other dignitaries attending the first summit conference of leaders from Latin America, Spain and Portugal to take place in this long-isolated nation. But much attention was diverted from the aging revolutionary by Cuba's political dissidents, who held unprecedented meetings with visiting officials to seek support for human rights reforms.

Since foreign leaders began arriving on the island over the weekend for Tuesday's gathering, activists have pressed their case in private discussions with the prime minister of Spain, the presidents of Portugal and Uruguay and the foreign ministers of Mexico, Nicaragua, Costa Rica and Panama. The meetings were the first of their kind since Castro, 73, seized power four decades ago and built a one-party state that has suppressed internal opposition that it views as inspired and supported by the U.S. government.

Several foreign leaders also met with the Rev. Jaime Ortega, archbishop of Havana, who has been moderately critical of many of Castro's policies.

Speaking at a news conference Friday, Foreign Minister Felipe Perez decried the Cuban dissidents as "a creation of the government of the United States . . . the point of the lance, the marionettes instructed and paid" by Washington.

Emerging this afternoon from talks with dissident leaders at the Spanish Embassy in Havana, Prime Minister Jose Maria Aznar of Spain said he shares the activists' position on "respect for human rights, democratic values and freedom" in Cuba. Aznar, whose past criticisms of Castro have strained relations between the two countries, also called for immediate release of political prisoners from Cuban jails.

"Over the last year, the government has been responsible for one of the largest waves of political repression against the peaceful and small internal opposition in 20 years," said Elizardo Sanchez, one of Cuba's leading dissidents. He said the meeting with foreign leaders has given "human recognition and moral support" to the anti-Castro groups.

The meetings with the dissidents have occurred despite a recent crackdown on some political opponents who Cuba says set out to sabotage this year's Ibero-American Summit at the behest of the U.S. government. In a drumbeat of denunciations overshadowing the main economic and social reasons for the annual gathering, Castro has accused Washington of urging participants to focus on Cuba's much maligned human rights record and instigating a recent campaign of dissident activity.

Foreign Minister Rosario Green of Mexico, the only Latin American nation that never severed diplomatic relations with Communist Cuba, contended that her meeting Sunday with Cuban dissidents, the first by a Mexican official, should not be misconstrued as an attempt to meddle in Cuba's affairs.

"Just as Cuban officials at all levels talk with Mexicans from all political views, I think Mexicans can also talk [with Cubans of differing political beliefs] without this. . . . being interpreted as something that it is not," she said.

Although all 21 member countries of the Ibero-American organization dispatched representatives, five presidents boycotted the event, including those from Costa Rica, El Salvador and Nicaragua. They stayed away to protest Cuba's human rights record and other political differences.

The presidents of Chile and Argentina also did not attend, because of their disapproval of Spain's effort to extradite and prosecute the former Chilean dictator, Gen. Augusto Pinochet.

More than 100 Castro opponents have been arrested, temporarily detained or ordered to stay at home during the gathering, according to dissident groups. And as Castro hosted the 16 high officials--as well as the king of Spain, who will take part in the one-day event--about 30 of the recently apprehended anti-government activists remained in jail, dissidents said.

A Foreign Ministry spokesman, however, said only 15 people are in custody for allegedly planning to disrupt the event.

For Cuba, the stakes are high. It is hosting the annual event for the first time since concerted efforts began in 1991 to foster political and economic cooperation among Spain, Portugal and their former Latin American colonies. The Castro government views the summit--whose central theme is the financial challenge of globalization--as a diplomatic achievement that affirms the country as a regional player despite attempts by the United States to isolate it through a 37-year-old commercial embargo.

The summit's agenda will include a broad mix of familiar themes, such as the need for greater relief of foreign debt, extraterritoriality and declines in foreign assistance. The transfer of the Panama Canal from the United States to Panama at the end of the year will also be discussed.

A State Department official said the United States would have preferred that the summit be held elsewhere but nevertheless hopes visiting heads of state will raise the issues of human rights, democracy and the need for an orderly post-Castro transition.

Special correspondent Marc Frank contributed to this report.

CAPTION: From left, Spanish Prime Minister Jose Maria Aznar and his wife, Ana Botella, Queen Sofia and King Juan Carlos join historian Eusebio Leal to view a statue of Columbus during the Spaniards' visit to Havana.

CAPTION: Cuban President Fidel Castro, right, greets Hugo Chavez, who was elected president of Venezuela last December, upon Chavez's arrival in Havana.