Cuba's vice president and Venezuela's leader gave optimistic assessments of Fidel Castro's health, saying the Cuban president was recovering quickly from intestinal surgery and could be expected back at work within a few weeks.

Castro has been out of sight since July 31, when his secretary announced he had undergone surgery and was temporarily ceding power to his younger brother, Defense Minister Raul Castro.

"In a few weeks he'll be recovered and he'll return to his duties," Vice President Carlos Lage said Sunday when asked by reporters when Castro would be back at work. Lage spoke in Bolivia, where he attended the Andean country's constitutional convention.

Castro's return would expose a U.S. policy of "lies" behind speculation that he would not recover from the operation, Lage said.

Cubans were told most details of Castro's health would be kept a state secret to prevent the island's enemies from taking advantage of his condition. Indeed, officials have failed to say what precisely is ailing Castro or what surgical procedure he underwent.

Lage earlier shot down reports that Castro had stomach cancer.

"The operation that he underwent was successful and he is recovering favorably," he said Sunday. "Fidel's going to be around for another 80 years."

Venezuelan President Hugo Chavez said Castro, who turns 80 next Sunday, was out of bed and talking following his surgery.

"How are you, Fidel?" Chavez said during his weekly TV and radio program, suggesting he believed the Cuban leader was watching. "We have reliable information of your quick and notable recuperation."

"Fidel Castro, a hug for you, friend and comrade, and I know you are getting better," he added.

Speaking by phone with Bolivian President Evo Morales later during the program, Chavez said Castro was bouncing back quickly.

"This morning I learned that he's very well, that he is already getting out of bed, he's talking more than he should — because he talks a lot, you know. He has sent us greetings," Chavez said.

Morales, a leftist elected in December as Bolivia's first Indian president, said he was glad to learn of Castro's recovery and that "what's left is for him to be incorporated into the battle of his country" again. Morales said Castro was like an "older brother."

Get-well wishes poured in from leftists across the hemisphere.

Former Nicaraguan President and Sandinista revolution leader Daniel Ortega arrived in Havana late Saturday. "I am sure that we will soon have Fidel resuming his functions and leading his people," Ortega said.

Colombia's largest rebel group also expressed its solidarity with the Cuban leader. "We hope you'll recover in the shortest time possible," the Revolutionary Armed Forces of Colombia said in a statement.

Secretary of State Condoleezza Rice said Sunday the United States wanted to help Cubans prepare for democracy but was not contemplating an invasion of the island in the wake of Castro's illness.

"The notion that somehow the United States is going to invade Cuba, because there are troubles in Cuba, is simply far-fetched," Rice told NBC News. "The United States wants to be a partner and a friend to the Cuban people as they move through this period of difficulty and as they move ahead. But what Cuba should not have is the replacement of one dictator by another."

Cuban authorities have beefed up security by mobilizing citizen defense militias, increasing street patrols and ordering decommissioned military officers to check in daily.

Roman Catholic Cardinal Jaime Ortega, the island's top churchman, called on parishioners Sunday to pray for Castro's health, peace on the island and fraternity among all Cubans, both here and abroad.

"We pray for the fatherland, for Cuba, and those who are leading it," Ortega told reporters after Sunday Mass at the cathedral in Old Havana.

Outside another church, a group of political prisoners' wives known as the Ladies in White held their weekly silent march without interruption by authorities.