The presidential election drew more than 80 percent of the population, council President Tibisay Lucena said on national television.
With more than 90 percent of the votes counted, Chavez, who first took office in 1999, had 54.43 percent of the vote and Capriles, a self-described moderate who vowed not to undo popular social programs, had 44.97 percent, she said.
Chavez presidential victory gives him another six-year term, until 2019.
Venezuelans had lined up for hours Sunday for the chance to vote, The
Washington Post reported. Lines of voters started to form before 5 a.m., an hour before polls opened, the newspaper said.
Various polls in recent days had predicted victory for the socialist Chavez, the Latin American Herald reported.
Since first being elected in 1998, Chavez has used the country's rich oil reserves to fund what he describes as modern socialism. While the United States is Venezuela's biggest trading partner, Chavez has consistently goaded Washington by aligning himself with the governments of Cuba, Iran and Syria.
"You can't do better than this president," Miguel Guevara, 77, who sells books in the streets and voted in a poor barrio whose support helped bring Chavez to power, told the Post. "The only one who has helped the country is named Hugo Chavez."
The 58-year-old has been undergoing treatment for an undisclosed type of cancer for the past year and a half. Faced by a challenger who just turned 40, Chavez posed for youthful photo opportunities in his campaign, including riding a motorcycle and doing a rap routine, CNN reported.
There were 18.9 million resident and expatriate Venezuelans eligible to vote.
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