MEXICO CITY, JULY 18 -- A crisis over Cuban asylum seekers at embassies in Havana intensified today as Cuba criticized a Spanish official who called for a "peaceful transition to democracy" on the island and Spain recalled its ambassador.

Meanwhile, a Cuban court convicted 11 human-rights activists of counterrevolutionary crimes, handing down sentences ranging from three to 15 years, according to the official Cuban news agency, Prensa Latina.

President Fidel Castro's government has struggled in recent days to end a stream of refugees to Havana embassies, but at least 13 reportedly remain at diplomatic missions of Spain, Czechoslovakia and Italy.

On Tuesday, Cuban police arrested a man on the grounds of the Swiss-monitored U.S. Interests Section, the former U.S. embassy in Havana. Washington protested the incident and issued a denial of Cuban charges that it was orchestrating recent events. "The U.S. government has no interest in encouraging Cuban citizens to seek refuge in foreign missions," it said.

Spain said it had recalled Ambassador Antonio Serrano de Haro for consultations, and accused Cuba of using language "removed from the customary niceties of international coexistence."

The tensions broke into the open earlier in the day when Spanish Foreign Minister Francisco Fernandez Ordonez suggested to reporters that Castro knew his regime would crumble if he opened the door to all Cubans who wanted to leave.

"The situation in Havana is very nervous due to Cuba's isolation from the world and because of the extremely serious economic problems there," Fernandez Ordonez told Spanish National Radio. "No one wants a catastrophe there. What is needed is a peaceful transition to democracy."

Cuba retaliated later in the day, issuing its own statement saying Spain had violated Cuban and international law by harboring asylum seekers. It said Cuba would never yield to "pressure or blackmail" by people seeking to leave the Caribbean island, Prensa Latina reported.

The Cuban statement also accused Spain's foreign minister of having an "attack of historical amnesia," a "scandalous lack of education about international law" and being "morally disqualified" from commenting on Cuban human rights. Castro's government has portrayed the asylum seekers as "antisocial elements."

Madrid sent a special security squad to Havana to reinforce security at the Spanish Embassy. Cuban police entered the grounds Friday in pursuit of a young asylum seeker and arrested him. As of today, four other Cubans were reportedly being sheltered inside the embassy, according to the Spanish news agency, EFE.

Albania, which like Cuba has held fast to authoritarian communism, recently allowed hundreds of people who entered foreign embassies in its capital to leave for the West.

In its report on the convictions, Prensa Latina said the 11 human-rights activists were found guilty of crimes ranging from terrorism and rebellion to having contacts with U.S. officials in Cuba. The dispatch said the defendants had planned to steal explosives to blow up the National Library and the Cuban Institute of Radio and Television.

The defendants were convicted after a 15-hour trial before a provincial judge. They were identified as members of Pro-Human Rights Youth, a group organized in 1989.