HAVANA — The Cuban government sought to reassure citizens after Fidel Castro temporarily ceded power for the first time in 47 years, releasing a statement from the world's longest-serving head of government saying his health is stable, his spirits good and the defense of the island guaranteed.

His brother and designated successor, Raul Castro, remained silent and out of sight, issuing no statements of his own.

"The important thing is that in the country everything is going perfectly well, and will continue to do so," said the statement by the elder Castro, who temporarily handed power to his brother on Monday night after surgery.

Castro, 79, acknowledged the operation was serious, saying "I cannot make up positive news." But he said his health was "stable" and "as for my spirits, I feel perfectly fine," according to the statement read on government television Tuesday night.

He apologized for not giving more details, but said the threat posed to his government by the U.S. means his health must be treated as "a state secret." No images of the leader were shown.