Venezuelan President Hugo Chavez died of a massive heart attack after great suffering and inaudibly mouthed his desire to live, the head of Venezuela's presidential guard said late Wednesday.

"He couldn't speak but he said it with his lips … 'I don't want to die. Please don't let me die,' because he loved his country, he sacrificed himself for his country," Gen. Jose Ornella told The Associated Press.

The general said he spent the last two years with Chavez, including his final moments, as Venezuela's president of 14 years battled an unspecified cancer in the pelvic region.

Ornella spoke to the AP outside the military academy where Chavez's body will lie in state until his funeral. The funeral had been scheduled for Friday but military officials told CBC journalists on the ground that it was being moved to Saturday.

Meanwhile, Ornella said Chavez's cancer was very advanced when death came but gave no details. He did not respond when asked if the cancer had spread to Chavez's lungs.

The government announced on the eve of Chavez's death that he had suffered a severe new respiratory infection. It was the second such infection reported by officials after Chavez underwent his fourth cancer surgery in Cuba on Dec. 11, 2012.

Venezuelan authorities have not said what kind of cancer Chavez had or specified exactly where tumors were removed.

During the first lung infection, near the end of December, doctors implanted a tracheal tube to ease Chavez's breathing, but breathing insufficiency persisted and worsened, the government said.

Ornella said that Chavez had "the best" doctors from all over the world, but that they never discussed the president's condition in front of him.

The general said he didn't know precisely what kind of cancer afflicted Chavez, but added: "He suffered a lot."

Venezuelan officials suspect foul play

He said that Chavez knew when he spoke to Venezuelans on Dec. 8, three days before his final surgery in Cuba, that "there was very little hope he would make it out of that operation."

It was Chavez's fourth cancer surgery and previous interventions had been followed by chemotherapy and radiation.

Ornella echoed the concern of Vice-President Nicolas Maduro, currently serving as the nation's interim president, that some sort of foul play was involved in Chavez's cancer.

A supporter of the late Venezuelan President Hugo Chavez holds a portrait of Chavez while waiting at the street as his coffin is driven through the streets of Caracas. Authorities have not yet said where Chavez will be buried after his state funeral. (Jorge Dan Lopez/Reuters)

"I think it will be 50 years before they declassify a document (that) I think (will show) the hand of the enemy is involved," he said.

The general didn't identify who he was talking about, but Maduro suggested possible U.S. involvement on Tuesday. The U.S. State Department called the allegation absurd.

Maduro, Chavez's self-anointed successor, said Chavez died Tuesday afternoon in a Caracas military hospital.

The government said Chavez, 58, had been there since returning from Cuba on Feb. 18.

Country's political future uncertain

Set against the outpouring of grief was near-total official silence on where Venezuela is heading next, including when the election will take place. Even the exact time and place of Chavez's funeral has not been announced, nor has it been revealed where he will be laid to rest.

Opponents already have been stepping up criticism of the government's questionable moves after Chavez's death, including naming Maduro, the vice-president, as interim president in apparent violation of the constitution, and the military's eagerness to choose political sides.

The 1999 constitution that Chavez himself pushed through mandates that an election be called within 30 days to replace a president, but Chavez's top lieutenants have not always followed the law.

A man, wearing a shirt with an image of the late Venezuelan President Hugo Chavez, holds a Venezuelan flag during a tribute for Chavez in Tegucigalpa, Honduras on Wednesday. (Jorge Cabrera/Reuters)

The charter clearly states that the speaker of the National Assembly, in this case Diosdado Cabello, should become interim president if a head of state is forced to leave office within three years of his election. Chavez was re-elected only in October.

But Chavez anointed Maduro for that role, and the vice president has assumed the mantle even as the government has named him as the ruling socialist party's candidate in the presidential vote.

The military also appears to be showing firm support for Maduro despite a constitutional mandate that it play no role in politics. In a tweet late Tuesday, state television said the defense minister, Adm. Diego Molero, had pledged military support for Maduro's candidacy against likely opposition candidate Henrique Capriles, raising concern among critics about the fairness of the vote.

Capriles, the 40-year-old governor of Miranda state who lost to Chavez in October, was conciliatory in a televised address after the president's death.

"This is not the moment to highlight what separates us," Capriles said. "This is not the hour for differences; it is the hour for union, it is the hour for peace."

Other opposition leaders were more critical of the military stance.

"When all Venezuela wants unity and peace, and a climate of respect between Venezuelans predominates, they're contrasted by what's unacceptable, the declarations of the minister of defence, that are, besides false, unconstitutional," said Ramon Guillermo Aveledo, executive secretary of the opposition coalition.

With files from CBC News and The Canadian Press