In the first official comment nearly a day after Cuban leader Fidel Castro handed temporary power to his brother, the president of Cuba's parliament indicated Castro's health was strong.
"The last moment of President Fidel Castro is still a long way off," Ricardo Alarcon said on Tuesday.
On Monday, the 80-year-old Castro issued an official announcement that he had acute intestinal bleeding and had to undergo a "complicated surgical operation".
In the absence of further official comment, wild speculation filled the airwaves, with a US senator wondering if Castro had died and Cuban exiles in Florida celebrating the possible demise of the communist leader.
"Imperialism does not recognise the greatness of Fidel Castro. He will fight until the last possible moment, although this last moment is still quite far off," Alarcon said.
Alarcon said Castro was recovering from delicate surgery and needed rest. But he noted that before handing power over to Raul Castro, 75, Fidel had issued orders from his sick bed that carefully delegated his responsibilities for education, health and energy to others, in order to fend off possible aggression by the US.
The move marked the first time that Castro has not held the reins of power in the one-party communist state since the 1959 Cuban revolution.
Alarcon, a member of the politburo of the Communist Party of Cuba (PCC), lashed out at the large celebrations on the streets of Miami in southern Florida, heavily populated with Cubans who fled Castro's regime just 150 km across the Caribbean.
Many hoped that he would soon die and others speculated that the Cuban government might be hiding his death.
Alarcon said he was sickened by the demonstrators, whom he called "mercenaries and terrorists".
"The (Cuban exiles) believe that they can just pack their suitcases and return to Cuba, just like they have done so often in the past - with no success," he said ironically.
Meanwhile, the US said it would not talk to Raul Castro to explore whether he wants to bring change to the communist island while filling in for his ailing brother, saying Raul had imposed himself on the Cuban people, "much the same as what his brother did".
US President George W Bush in 2003 set up a commission to explore ways to hasten the end of the Castro regime, plan for assisting a transition to democracy and address the humanitarian needs of Cubans if the regime collapses.
"In the event that Cuba does start to make a transition to a democracy, the US and the American people will do everything we can," US State Department spokesman Sean McCormack said.
The health of Castro, whose 80th birthday is August 13, has been the subject of frequent speculation in recent years.
Castro proposed that his birthday celebrations be by postponed until Dec 2, the 50th anniversary of the beginning of the 1956 uprising.