HAVANA - Fidel Castro, who has been in power in Cuba for nearly 50 years, told his people on Tuesday he was in good spirits and stable after undergoing surgery and temporarily relinquishing power to his brother. 

Cuban President Fidel Castro, left, and his brother, Minister of Defense Raul Castro, attend a Cuban Parliament session in the Palace of Conventions in this July 1, 2004, file photo in Havana, Cuba. It was announced, Monday, July 31, 2006, that Fidel Castro has temporarily relinquished presidential power to his brother Raul due to illness. [AP]

"I can say it is a stable condition, but a real evolution of the state of my health needs time," Castro, 79, said in a statement read out on state television. He did not appear on the screen.

"I am in perfectly good spirits," he said. "The most I can say is that the situation will remain stable during many days before a verdict can be given."

The ailing Cuban leader handed over the presidency temporarily to his younger brother Raul on Monday after having an operation to stop gastrointestinal bleeding.

Castro, who had claimed he delegated power because Cuba was under threat from the United States, said the Cuban armed forces were prepared to defend the nation.

Television journalist Randy Alonso said he spoke to Castro minutes before going on air and the Cuban leader asked him to broadcast his words to the nation.  

It also prompted speculation that Castro, who took power in 1959, would not return to office.

In Washington, the Bush administration, which has tightened the decades-long U.S. embargo with Cuba, dismissed any possibility of a softer stance toward the provisional new leader Raul Castro.

Brazilian President Luiz Inacio Lula da Silva, a long-time friend of Castro, said Cubans alone should decide on a possible presidential successor.

"The succession process is a decision the Cuban people will have to take," Lula told reporters in Brasilia. He added that Castro may recover and that "the situation may not be as bad as it appears."

In Cuba, where Castro's guerrillas once swept down from the Sierra Maestra hills to overthrow a U.S.-backed dictator, word of his illness brought apprehension over the future of the Caribbean island nation of 11 million.

Many Cubans, whether admiring of Castro or not, seemed stunned by the temporary exit of a figure who has run their lives for decades.

There was no sign in public of Raul Castro, 75, long-time defense minister who has now taken over his brother's posts of Communist Party head, armed forces' commander-in-chief and president of the executive Council of State.

Party officials expressed support for Raul, an ex-guerrilla who has spend decades in his brother's shadow and is seen as ensuring continuation of the one-party political system.

"Raul is a revolutionary leader without doubt and the revolution is safe with him," said Armando Diaz, a local party leader in Havana, dressed in green fatigues.

Castro, who last appeared in public giving a July 26 speech, said in a "proclamation" read out by an aide on television on Monday that his ill health was caused by overexerting himself during travels last month.

His health has been an issue since he fainted during a speech in 2001.

Cubans went about their lives calmly with no sign of increased police presence in Havana.

Venezuela, whose leftist President Hugo Chavez said in a statement that Castro's recovery was "advancing positively," citing information from the Cuban government.

But medical experts said surgery for major bleeding in a elderly man is risky and could require several months of rest.