Vice President Nicolas Maduro surprised Venezuelans with a Christmas Eve announcement that President Hugo Chavez is up and walking two weeks after cancer surgery in Cuba, but the news did little to ease uncertainty surrounding the leader's condition.

Sounding giddy, Maduro told state television Venezolana de Television that he had spoken by phone with Chavez for 20 minutes Monday night. It was the first time a top Venezuelan government official had confirmed talking personally with Chavez since the Dec. 11 operation, his fourth cancer surgery since 2011.

"He was in a good mood," Maduro said. "He was walking, he was exercising."

Chavez supporters reacted with relief, but the statement inspired more questions, given the sparse information the Venezuelan government has provided so far about the president's cancer. Chavez has kept secret various details about his illness, including the precise location of the tumors and the type of cancer. His long-term prognosis remains a mystery.

Dr. Michael Pishvaian, an oncologist at Georgetown University's Lombardi Cancer Center in Washington, said it was an encouraging sign that Chavez was walking, and it indicated he would be able to return to Venezuela relatively soon. But he said the long term outlook remained poor.

"It's definitely good news. It means that he is on the road to recover fully from the surgery," Pishvaian said in a telephone interview with The Associated Press. "The overall prognosis is still pretty poor. He likely has a terminal diagnosis with his cancer that has come back."

Pishvaian and other outside doctors have said that given the details Chavez has provided about his cancer, it is most likely a soft-tissue sarcoma.

Chavez first underwent surgery for an unspecified type of pelvic cancer in Cuba in June 2011 and went back this month after tests had found a return of malignant cells in the same area where tumors were previously removed.

Venezuelan officials said that, following the six-hour surgery two weeks ago, Chavez suffered internal bleeding that was stanched and a respiratory infection that was being treated.

Maduro's announcement came just hours after Information Minister Ernesto Villegas read a statement saying Chavez was showing "a slight improvement with a progressive trend."

Dr. Carlos Castro, director of the Colombian League against Cancer, an association that promotes cancer prevention, treatment and education, said Maduro's announcement was too vague to paint a clear picture of Chavez's condition.

"It's possible (that he is walking) because everything is possible," Castro told AP. "They probably had him sit in up in bed and take two steps."

"It's unclear what they mean by exercise. Was it four little steps?" he added. "I think he is still in critical condition."

Maduro's near-midnight announcement came just as Venezuelan families were gathering for traditional late Christmas Eve dinners and setting off the usual deafening fireworks that accompany the festivities. There was still little outward reaction on a quiet Christmas morning.

Danny Moreno, a software technician watching her 2-year-old son try out his new tricycle, was among the few people at a Caracas plaza who said she had heard Maduro's announcement. She said she saw a government Twitter message saying an announcement was coming and her mother rushed to turn on the TV.

"We all said, thank God, he's okay," she said, smiling.

Dr. Gustavo Medrano, a lung specialist at the Centro Medico hospital in Caracas, said if Chavez is talking, it suggests he is breathing on his own despite the respiratory infection and is not in intensive care. But Medrano said he remained skeptical about Maduro's comments and could deduce little from them about Chavez's prognosis for recovery.

"I have no idea because if it was such a serious, urgent, important operation, and that was 14 days ago, I don't think he could be walking and exercising after a surgery like that," Medrano said.

Over the weekend, Chavez's ally, Bolivian President Evo Morales, made a lightning visit to Cuba that only added to the uncertainty.

Journalists had been summoned to cover his arrival and departure in Havana, but hours later that invitation was canceled. No explanation was given, though it could have been due to confusion over Morales' itinerary as he apparently arrived later than initially scheduled.

Cuban state media published photos of President Raul Castro receiving Morales at the airport and said he came "to express his support" for Chavez, his close ally, but did not give further details. He left Sunday without making any public comments.

For the second day in a row Tuesday, Morales made no mention of his trip to Cuba during public events in Bolivia.

Yet more questions surround Chavez's political future, with the surgery coming two months after he won re-election to a six-year term.

If he is unable to continue in office, the Venezuelan Constitution calls for new elections to be held. Chavez has asked his followers to back Maduro, his hand-picked successor, in that event.

Venezuelan officials have said Chavez might not return in time for his Jan. 10 inauguration.

Opposition leaders have argued that the constitution does not allow the president's swearing-in to be postponed, and say new elections should be called if Chavez is unable to take the oath on time.

But government officials have said the constitution lets the Supreme Court administer the oath of office at any time if the National Assembly is unable to do it Jan. 10 as scheduled.

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Associated Press writers Peter Orsi in Havana, Vivian Sequera in Caracas, Camilo Hernandez in Bogota, Colombia, and Paola Flores in La Paz, Bolivia, contributed to this report.