Exit polls in Venezuela's referendum indicate that Hugo Chavez, the president, has won support to scrap term limits for elected officials, including himself.

Several pollsters gave the "yes" vote between 53 and 60 per cent on Sunday, meaning that Chavez could seek re-election indefinitely.

Polling stations remained opened past the official closing time to allow all voters already in line to cast their ballots.

More than 16 million Venezuelans were eligible to vote "Yes" or "No" in the fifth referendum since Chavez was first elected in 1999.

Festive mood

Al Jazeera's Mariana Sanchez, reporting from close to the presidential palace in Caracas, said there was a festive mood on the streets of the capital as Chavez supporters already began celebrating late on Sunday.

But the head of the election commission called for calm, saying that official results were not out yet.

The referendum is Chavez's second attempt to remove the two-term cap for presidents. If approved, it would allow Chavez to seek election when his current second term in office ends in 2013.

After casting his vote at a polling station in a Caracas slum, Chavez promised to abide by the outcome.

"We'll recognise the result, whatever it is, once it is announced by the National Electoral Council," he said.

Chavez has previously described winning the vote as key to completing his transformation of Venezuela into a socialist state.

"On Monday I'll wake up looking beyond 2013," Chavez said. "That will give me more confidence in what we're doing ... and greatly diminish political uncertainties."

Popular among poor

Spearheaded by a student movement, the opposition's campaign slogan is "No is No," referring to Chavez's 2007 effort to push through constitutional changes that would extend his presidency.

Chavez lost that vote, his only electoral defeat in 10 years in office.

"My certainty in victory is infinitely higher than on December 1, 2007," Chavez said.

Chavez is popular with many of the country's poor for health and education programmes, but blamed by a vocal opposition for rising crime, corruption and inflation.

His opponents say a victory for Chavez in the referendum would remove the last remaining check on his power.

Oscar Perez, a representative of the opposition, called Chavez's government "fascist" and "intolerant".

The opposition says Chavez called the vote - which takes place only three months after the opposition gained ground in regional and municipal elections - before the country feels the impact of falling oil prices, the main source of funding for the president's social programmes.

With a strong grasp on the private media, the opposition has focused its campaign on the importance of alternating power for democracy in their campaign, and accused Chavez of abusing state resources to fund a massive "Yes" campaign.

Voters undecided

Rob Winder, also reporting for Al Jazeera from Caracas, said both campaigns appeared confident that they can claim victory, but that the "Yes" camp believed more of their supporters were turning out to vote.

He said while groups of young Chavez supporters patrolled the streets on motorcycles, the "No" campaign seemed to have adopted a low-key approach, concentrating instead on monitoring how the vote has been conducted.

About 100 international observers have been accredited to observe the referendum, but neither the Organisation of American States (OAS) nor the European Union have official observers in Venezuela.