Bolivian President Evo Morales made a lightning trip this weekend to Havana where ally Hugo Chavez is convalescing after cancer surgery, but was mostly silent Monday on the details of his trip or even whether he met with the ailing Venezuelan leader.

The secrecy surrounding his visit was sure to add to the uncertainty surrounding Chavez's condition, despite reassurances Monday from Venezuelan officials that the president was slowly improving.

The Venezuelan leader has not been seen or heard from since his Dec. 11 surgery. Venezuelan officials have given few specifics about his condition and have offered no information about his long-term prognosis.

Luis Vicente Leon, a pollster who heads the Venezuelan firm Datanalisis, said the government's daily but vague updates on the president's health seem designed to calm anxious Chavez supporters rather than keep the country fully informed. For government opponents, however, he said the updates likely raise more questions than they answer.

"It's more for the Chavez movement than the country in general," Leon said. "There's nothing that one can verify, and the credibility is almost nil."

Morales did not speak to the foreign media while in Havana. Journalists had been summoned to cover his arrival and departure, 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.

At an event in southern Bolivia on Monday, Morales made no mention of his trip to Cuba, even though aides had told reporters that he might say something about Chavez's recovery. Later, Morales' communications minister did not respond directly to a question about whether the two South American presidents had met face-to-face, saying only that he "was with the people he wanted to be with" and had no plans to return to Cuba.

"The report that President Morales has given us is that Chavez is in a process of recovery after the terrible operation he underwent," Amanda Davila told The Associated Press.

Morales is the second Latin American leader to visit since Chavez announced two weeks ago that he would have the operation. Rafael Correa of Ecuador came calling the day of the surgery. Uruguay's Jose Mujica has expressed interest in making the trek.

The visits underscore Chavez's importance to regional allies as a prominent voice of the Latin American left, as well as how seriously they are taking his latest bout with cancer.

Chavez underwent his fourth cancer-related operation of the last year-and-a-half on Dec. 11, two months after winning reelection to a six-year term. Venezuelan officials say Chavez is stable and his recovery is progressing, though he was treated for a respiratory infection apparently due to the surgery.

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

In Caracas, Venezuelan Information Minister Ernesto Villegas read a statement Monday saying that Chavez is showing "a slight improvement with a progressive trend," is keeping up with events back home and sends Christmas greetings to Venezuelans.

Maduro and several Cabinet ministers attended a Christmas Eve Mass in Caracas to pray for the president. Maduro again assured Venezuelans that the president was recovering, though he and other officials continued to strongly suggest that Chavez would 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 Attorney General Cilia Flores insisted 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.

"Those who are counting on that date, hoping to thwart the Revolution and the will of the people, will end up frustrated once again," Flores said. "What we have is a president who has been re-elected, he will take over, will be sworn in on that day, another day, that is a formality."

Jaqueline Farias, the head of government for the Caracas area, told the AP outside the church that "we are very happy because each hour the `commandante' is showing signs that he is overcoming this phase of the operation, his fourth operation."

When asked if the president was breathing on his own, she said she didn't know and walked off, refusing to answer more questions.

Dozens of Chavez supporters gathered outside the church, some carrying posters of the president or wearing red T-shirts decorated with a photograph of just Chavez's eyes. Some women rushed to the church after seeing footage of the Mass on state television and yelled at security guards to let them inside.

"Chavez is going to be mad, if he sees this," said Andres Sanchez, an unemployed Chavez supporter watching a woman shouting at a guard that she wanted to pray for Chavez, too. "He told the ministers to talk to the people."

"Venezuela without Chavez is like a ship without a rudder," Sanchez said, his voice wobbling. "I pray to God that he recovers because he is a man who loves the people, the children, the elderly and everyone a little bit."

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Olson reported from Caracas, Venezuela. Associated Press writers Christopher Toothaker and Vivian Sequera in Caracas and Paola Flores in La Paz, Bolivia, contributed to this report.

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