CARACAS, Venezuela (AP) -- Venezuela's opposition demanded that the government reveal specifics of President Hugo Chavez's condition Wednesday, criticizing secrecy surrounding the ailing leader's health more than three weeks after his cancer surgery in Cuba.

Opposition coalition leader Ramon Guillermo Aveledo said at a news conference that the information provided by government officials "continues to be insufficient."

Chavez has not been seen or heard from since the Dec. 11 operation, and Vice President Nicolas Maduro on Tuesday said the president's condition remained "delicate" due to complications from a respiratory infection.

Maduro also urged Venezuelans to ignore rumors about Chavez's condition.

Aveledo said the opposition has been respectful during Chavez's illness, arguing that "the secrecy is the source of the rumors."

"They should tell the truth," Aveledo said, noting that Maduro had pledged to provide full reports about Chavez's condition. He reiterated the opposition's call for the government to release a medical report and said all indications are that Chavez won't be able to be sworn in to begin a new term Jan. 10.

If Chavez can't take office on that date, Aveledo said the constitution is clear that the National Assembly president should then take over temporarily until a new election is held. He said what happens next in Venezuela should be guided by "the truth and the constitution."

If Chavez dies or is unable to continue in office, the Venezuelan Constitution says a new election should be held within 30 days.

With rumors swirling that Chavez had taken a turn for the worse, Maduro said on Tuesday that he had met with the president twice, had spoken with him and would return to Caracas on Wednesday.

"He's totally conscious of the complexity of his post-operative state and he expressly asked us ... to keep the nation informed always, always with the truth, as hard as it may be in certain circumstances," Maduro said in the prerecorded interview in Havana, which was broadcast Tuesday night by the Caracas-based television network Telesur.

Both supporters and opponents of Chavez have been on edge in the past week amid shifting signals from the government about the president's health. Officials have reported a series of ups and downs in his recovery -- the most recent, on Sunday, announcing that he faced the new complications from a respiratory infection.

Maduro did not provide any new details about Chavez's complications during Tuesday's interview. But he joined other Chavez allies in urging Venezuelans to ignore gossip, saying rumors were being spread due to "the hatred of the enemies of Venezuela."

He didn't refer to any rumors in particular, though one circulating online had described Chavez as being in a coma.

Maduro said Chavez faces "a complex and delicate situation." But Maduro also said that when he talked with the president and looked at his face, he seemed to have "the same strength as always."

"All the time we've been hoping for his positive evolution. Sometimes he has had light improvements, sometimes stationary situations," he said.

Maduro's remarks about the president came at the end of an interview in which he praised Cuba's government effusively and touched on what he called the long-term strength of Chavez's socialist Bolivarian Revolution movement. He mentioned that former Cuban President Fidel Castro had visited the hospital where Chavez was treated.

In Washington, the U.S. State Department said procedures under the Venezuelan Constitution should be followed if Chavez is no longer able to carry out his duties as president.

"We want to see any transition take place in a manner that is consistent with the Venezuelan Constitution, that any election be fully transparent, democratic, free and fair," State Department spokeswoman Victoria Nuland told reporters on Wednesday.

Asked if Chavez being out of the picture would make it easier to improve long-strained ties between Venezuela and the U.S., Nuland said, "Obviously we will judge our ability to improve our relationship with Venezuela based on steps they are able to take."

The U.S. Embassy in Caracas has been without an ambassador since July 2010. Chavez rejected the U.S. nominee for ambassador, accusing him of making disrespectful remarks about Venezuela's government. That led Washington to revoke the visa of the Venezuelan ambassador.

But recently U.S. and Venezuelan diplomats began high-level conversations aimed at improving relations, a U.S. government official said. The official spoke on condition of anonymity because he wasn't authorized to speak publicly about the matter.

The official confirmed recent reports that Roberta Jacobson, assistant secretary of state for Western Hemisphere affairs, spoke by telephone with Maduro in November and discussed ways of improving relations. He also confirmed that U.S. diplomat Kevin Whitaker had a subsequent conversation with Roy Chaderton, Venezuela's ambassador to the Organization of American States.

Venezuelan diplomats could not be reached to comment about those recent contacts with U.S. officials.

In Bolivia, meanwhile, President Evo Morales said he is concerned about his friend and ally.

"I hope we can see him soon," Morales said at a news conference Wednesday. "But it's a very worrying situation."

"I've tried to make contact with the vice president, and it's been difficult. I hope all of their aims are achieved to save President Chavez's life."

Before his operation, Chavez acknowledged he faced risks and designated Maduro as his successor, telling supporters they should vote for the vice president if a new presidential election was necessary.

Maduro didn't discuss the upcoming inauguration plans, saying only that he is hopeful Chavez will improve.

"Someone asked me yesterday by text message: How is the president? And I said, 'With giant strength,'" Maduro said. He recalled taking Chavez by the hand: "He squeezed me with gigantic strength as we talked."

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Associated Press writers Jorge Rueda in Caracas, Luis Alonso Lugo in Washington and Paola Flores in La Paz, Bolivia, contributed to this report.

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Ian James on Twitter: http://twitter.com/ianjamesap