HAVANA (Reuters) -- Cuban leader Fidel Castro is recovering satisfactorily from stomach surgery, the country's vice president said on Saturday, while government sources said he had started to eat and sit up in bed.

Brazilian officials denied a newspaper report they had been told by Cuban authorities the veteran revolutionary had a malignant stomach tumor and may never be able to return fully to power.

Vice President Carlos Lage, speaking on a trip to Bolivia, was the third Cuban official in the past two days to reassure the Communist-ruled nation that Castro was on the mend from surgery for internal bleeding.

But he gave no further details in the report by the Cuban state news agency Prensa Latina.

"I was told Fidel is doing better, he has eaten something and sat up," one source told Reuters, asking not to be identified.

Mid-level Communist Party officials were informed that Castro was out of intensive care and beginning to recover, a party source said in Santiago, Cuba's second largest city.

In Brazil, the Folha de S.Paulo newspaper reported that Brazilian President Luiz Inacio Lula da Silva and members of the ruling Workers' Party had been told by Cuban officials that Castro had a malignant stomach tumor and his condition was worse than has been publicly admitted.

A Brazilian government spokesman said the report was unfounded.

In Caracas, a government source said Venezuelan President Hugo Chavez was now unlikely to fly to Havana this weekend to see his friend Castro.

U.S. Secretary of State Condoleezza Rice, in a message beamed to Cuba on Friday night, told the island's residents that "much is changing there" and now was the time to push for democracy.

But Cuba's culture minister, Abel Prieto, told reporters at a Havana event Rice's message, which followed a similar statement by President George W. Bush, would fall on deaf ears.

"Nobody in Cuba is going to listen to a message that comes from a functionary of a foreign government," he said.

"Nobody in Cuba is going to listen to a message that comes from a functionary of a foreign government. That has no value for Cubans," he said in some of the first government comments since Castro's surgery.

"I don't feel any uncertainty. The people love Fidel a lot and that has been seen in these days," he said.

A Cuban-American lawmaker said also Spain should move to support a democratic transition in Cuba.

Castro, 79, stunned his country by announcing on Monday that he had ceded power temporarily to his younger brother, Raul Castro, after undergoing surgery to stop intestinal bleeding.