Demonstrating he retains firm control over Cuba (search) after fracturing his knee and arm in a fall at a public event, President Fidel Castro (search) told of conducting government business by cellular phone during an ambulance ride and later refusing general anesthesia.

"I have not stopped attending to the tasks that I am responsible for, in coordination with the other comrades," Castro, 78, wrote in a lengthy note read Thursday night on state television.

Castro said he underwent a 3 hour, 15 minute operation to repair his left knee, which was broken in eight pieces, and the immobilization of his left upper arm, which suffered a hairline fracture.

He said he remained awake the whole time, anesthetized only from the waist down, so he could "attend to numerous important issues" with his chief of staff, who dressed in surgical scrubs.

Castro said earlier he remained in contact with his office via cellular phone during the ambulance ride back to Havana (search) from Santa Clara, the central city about a three-hours drive away where the accident occurred.

Castro's message seemed to be aimed at clearing up any doubts about his ability to govern this communist nation of 11.2 million people after 45 years in power.

His advancing age — and ultimately his mortality — was brought home when he was injured Wednesday night when he tripped and fell after a speech at the Santa Clara graduation ceremony.

But Castro has fought to dispel concerns about his health and his ability to keep governing.

"I'm all in one piece," Castro declared on state television Wednesday just minutes after he fell.

A medical examination early Thursday confirmed Castro suffered a broken left knee and a hairline fracture in his upper right arm, said an official notice carried by state media.

"His general health is good, and he is in excellent spirits," it said, adding that Castro hoped to be "back in place" soon.

Castro's health has long been closely watched — particularly by his political enemies in Miami, home to a large Cuban exile community.

"Sometimes, people have this idea that he's some sort of god, that he's omnipotent," said Yanisset Rivero, spokeswoman for the Cuban Democratic Directorate, a Miami group that supports dissidents on the island. "It's a sign ... that he's human."

Rights activist Elizardo Sanchez of Havana predicted the incident would not immediately affect government policies, but it "does put on the agenda the theme of the advanced age of various leaders."

In the last several years, Castro's knees have seemed more wobbly, his step less steady. Nevertheless, he maintains a busy schedule that frequently includes all-night meetings with aides and visitors.

Average Cubans did not seem as alarmed Thursday as they were three years ago, when Castro fainted in the scorching Caribbean sun during a live televised speech before a crowd of thousands.

"He needs to get well soon," Georgina Hernandez said Thursday as she walked on the streets of Old Havana. "The Cuban people need him and need him to last a long time."

In Washington, the State Department declined to wish a speedy recovery to Castro, who has remained in power during 10 American administrations.

"We, obviously, have expressed our views about what's broken in Cuba," said spokesman Richard Boucher.

The June 23, 2001, incident in which Castro collapsed behind the podium several hours into a speech prompted many Cubans for the first time to reflect on, and openly discuss, Castro's mortality and their country's future.

Castro's designated successor has long been his brother, 73-year-old Defense Minister Raul Castro, who fought with him in the Cuban revolution that overthrew President Fulgencio Batista on Jan. 1, 1959.

Raul Castro is first vice president of both the government's ruling Council of State and of the Communist Party — directly after his brother. The constitution does not specify a No. 3 in the presidential succession.

Also mentioned as possible successors have been Foreign Minister Felipe Perez Roque, 39, a former personal secretary to Castro, and Vice President Carlos Lage, 53, who as Cabinet secretary has broad experience in helping oversee the economy and government.

Exclusive APTN footage of Castro's fall on Wednesday showed the Cuban leader tripped after descending the stairs from the stage after his speech and fell forward, hard on his right side.

Cubans watching on state television did not see the fall, only security men running off to the side.

Aides and security agents immediately surrounded the president and helped him to a folding chair.

"I will do what is possible to recover as fast as possible, but as you can see I can still talk," Castro told television viewers. "Even if they put me in a cast, I can continue in my work."