Cuba sought to reassure the world that Fidel Castro was not on his deathbed last night, as the US Government, alongside exiles and commentators, began openly discussing the post-Castro future of the island.

In a statement read on Mesa Redonda Informativa, or "News Round Table", a political chat show, the Cuban President said that he was in "perfectly good spirits" but added that it would several days before his condition was fully known.

Cuba was stunned on Monday night by the news that Señor Castro, who is 79, had temporarily handed power to his younger brother Raúl, 75, while he underwent surgery for sustained gastrointestinal bleeding.

Señor Castro, who took power in 1959 and has outlasted nine American presidents, is not expected to resume his presidential duties for months.

At the end of a day of furious rumours — including speculation that Señor Castro was already dead — the Cuban President decided to speak through Randy Alonso, the host of Mesa Redonda Informativa and one of the country's most recognisable journalists.

No pictures of Señor Castro were shown, and El Comandante, as he is known, asked his fellow Cubans to understand that the precise nature of his illness was a state secret, "owing to the plans of the Empire", a reference to the US.

"I can say that the situation is stable, but a real evolution in the state of my health needs time," the Cuban leader said in his statement. "The most I would be able to say is that the situation has to remain stable for many days before a verdict can be given."

Señor Castro thanked well wishers from the around the world for their messages of support. "I am in good perfectly good spirits," he said. "The important thing is that the country is working perfectly well and the Revolutionary Armed Forces and the people are prepared to defend it."

Señor Alonso, a leader in Cuba's communist youth movement, implied that the President was in a stable condition by mentioning that he had spoken to him on the telephone just before coming on air.

The President of Cuba's National Assembly, Ricardo Alarcon, said: "The Cuban leader will always fight until the last moment. But that last moment is very far away," he said.

Havana remained calm and quiet yesterday as Cubans, reluctant to speak in the open about the fading of Señor Castro, digested the news. The temporary promotion of Raúl Castro, regarded for decades as a natural, if less popular, deputy for his brother came as no surprise.

But in a sign of possible fears of unrest, local government youth organisations, known as military committees, were mobilised to maintain order, according to Cuba Net, an independent news source on the island.

Caution and silence in Havana contrasted sharply with raucous celebration in Miami, where Cuban exiles and anti-Castro activists hoped the handover of power marked the beginning of the final days of the Castro Government.

In Washington, the Bush Administration, which has maintained the 44-year-old US embargo of the island, reiterated its desire for a change of regime in Cuba. The White House spokesman, Tony Snow, said there were "no plans to reach out" to Raúl Castro, should he take permanent control.

"The one thing that this President has talked about from the very beginning is his hope for the Cuban people finally to enjoy the fruits of freedom and democracy," said Mr Snow. "And for the dictator, Fidel Castro, to hand off power to his brother, who’s been the prison keeper, is not a change in that status."

But the American press took the opportunity to call for a lifting of the embargo, which Cuban officials estimate costs the island around $1 billion a year, and called on President Bush to play a constructive role in any transitional government.

The New York Times said Mr Bush should ease the trade restrictions and look beyond the demands of the vehemently anti-Castro exiles who lead America's Cuban dissident groups:

"Ten successive American presidents have proclaimed their fervent desire for a Cuba without Fidel Castro. If he can transcend the ideological fixations of the exile community, President Bush could become the first of.them with a real chance to help Cubans build a better, post-Castro future," the newspaper wrote today.

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