By Anthony Boadle
CARACAS, April 23 (Reuters) - Officials in President Hugo Chavez's government denied rumors that the leftist leader may have died while undergoing cancer treatment in Cuba six months ahead of an election in South America's top oil exporter.
In the nine days since he left for Havana to have two final radiation sessions for an undisclosed cancer, Chavez has only addressed Venezuelans by short messages on Twitter to cheer supporters and hail the advances of his socialist "revolution."
His unusually long silence - during previous trips to Cuba the verbose Chavez has made phone calls to state television - has stirred speculation about his health and doubts over his condition as he campaigns for re-election in an Oct. 7 vote.
In the past, Havana published pictures and video of him meeting his mentor, former Cuba leader Fidel Castro. There have no been no images released from this visit, so far.
Opposition candidate Henrique Capriles leapt to the attack and complained that Chavez was running the country remotely by Twitter from a hospital on the communist-led Caribbean island.
Chavez's political ally and president of the National Assembly legislature Diosdado Cabello dismissed the rumors in a tweet: "The truth is that these embittered people don't learn. They've been saying for days that the Comandante died."
"The only thing that is lifeless here is that loser," Cabello said, referring to Capriles, the opposition's best hope for defeating Chavez and ending his 13 years in power.
Cabello said on Sunday that the president was recovering and would return this week to Venezuela, where he is expected to sign a new labor law that shortens the work week and extends workers' benefits and is due to go into effect on May 1.
Even opposition journalist Nelson Bocaranda, who has often broken news on Chavez's treatment in the absence of official details from the government, helped to cast doubt on the rumors.
Bocaranda tweeted that the 57-year-old leader watched the Barcelona-Real Madrid soccer game on Saturday with his daughters in Havana.
Venezuelan government officials insist Chavez is fully in touch and capable of governing the country from Cuba.
Science and Technology Minister Jorge Arreaza said on Twitter that he and Foreign Minister Nicolas Maduro worked with Chavez on Sunday and the president approved various projects.
'GOVERNING BY TWITTER'
Capriles, a youthful state governor who is the opposition's "unity candidate" to face Chavez, sharply criticized the all-dominant leader for not doing his job properly.
"Governing by Twitter, approving laws by Twitter without consulting anybody, is an insult to our people. The country's problems cannot be resolved by Twitter," Capriles said.
Before leaving for Cuba on April 14, Chavez acknowledged that radiation therapy was physically tiring and he skipped the Summit of the Americas in Colombia that weekend on the advice of his doctors.
Chavez's opponents have criticized him for keeping the country in the dark about the extent of his illness, raising suspicions that his cancer may have spread from an initial baseball-sized tumor that was removed from his pelvis.
Despite his cancer, Chavez is seeking a new six-year term at an election that is shaping up to be the toughest political fight of his career due to his ill health and a serious opposition challenge.
His government faces potentially embarrassing revelations about links to drug trafficking from a former Supreme Court justice who fled the country and has reportedly become a U.S. Drug Enforcement Administration informant.
Chavez remains very popular among poorer Venezuelans who have benefited from his social programs, which redistribute some of the country's vast oil wealth.
Almost all recent opinion polls have given Chavez a comfortable double-digit lead over Capriles, and his frequent trips to Cuba for treatment appear not to have changed that.
A survey released on Monday by local pollster Hinterlaces showed 53 percent of Venezuelan voters planning to back Chavez in October, versus 34 percent for Capriles, a one-percentage point gain for the president since a similar poll last month.
"Although President Chavez is not present in the media, his illness is the talk of the nation," said Hinterlaces director Oscar Schemel, who added that emotional factors are working in Chavez's favor in the run-up to the election. (Additional reporting by Diego Ore; Editing by Daniel Wallis)