Venezuelan opposition leader Henrique Capriles has called on electoral authorities to suspend plans to proclaim acting President Nicolas Maduro the winner of an election to succeed the late Hugo Chavez.
Repeating his call for a vote recount, Capriles said on Monday that Maduro would be an "illegitimate president" if he was declared the winner.
He urged Venezuelans to bang their kitchen pans later on Monday if the proclamation goes forward - a popular Latin American form of protest known as a "cacerolazo" - to "let the world know our outrage, our anger."
Capriles' call comes moments before Nicolas Maduro is to be formally proclaimed winner of the presidency by the election board at a ceremony and rally in Caracas, despite opposition demands for a total recount.
State media called on Venezuelans to attend the event in the business district of Caracas at 2 pm local time (1830 GMT) on Monday after Maduro's narrow win in Sunday's vote.
The National Electoral Council said late on Sunday that Maduro won 50.66 percent of the vote compared to 49.07 percent for Capriles - a difference of less than 300,000 ballots - allowing him to carry forward the policies of the late Hugo Chavez.
Venezuela uses electronic voting machines that print a paper ballot as a back-up for any recounts.
"There should be no doubts about the election results," Maduro said addressing a crowd from the Miraflores presidential palace.
|Socialist candidate Nicolas Maduro addresses a crowd after winning the presidential poll by a slim margin
"The institutions are functioning. If 7,500,000 Venezuelans said that Nicolas Maduro should be the president of the republic until 2019, this must be respected - the democracy and the power of the majority."
Maduro, however, said he would welcome an audit.
"We are calling for respect of the results," he said.
"If they want do an audit they are welcome to do it. They can do whatever audit they want to do. We trust in the Venezuelan electoral system. We welcome an audit."
After a brief and bitter campaign, Venezuelans had waited anxiously for results into Sunday night with counting reportedly too close to call and both sides expressing confidence of victory.
Earlier Al Jazeera's Gabriel Elizondo, reporting from Caracas, said: "We are hearing that Maduro is going to try and take the presidency today, Monday, and be inaugurated.
"We'll see how that plays out because I'm sure the opposition is going to try and step in and say perhaps that they want a full audit before that happens. There is a long way for this to go still, the coming days are going to be key."
Capriles said there were attempts to let people vote after polling stations had already closed.
Turnout was 78 per cent, down from just over 80 per cent in the October election that Chavez won by a near 11-point margin.
"This result does not reflect the reality of what Venezuelans want and aspire to," he said in Caracas.
"Mr Maduro, if you were illegitimate before, now you are more so.
"I tell you firmly, this struggle is not over. It will end when Venezuela is a prosperous country when people can live better."
It was unclear when a recount might start, and how long it would last.
"We demand a detailed recount in front of the world and the country," Capriles said.
Earlier, Capriles accused the government of pressuring civil servants to vote for Maduro.
Maduro inherited Chavez's formidable electoral machinery, which helped the late leader win successive elections in 14 years, with government employees often seen handing campaign pamphlets and attending rallies in groups.
Both candidates had pledged during the campaign to recognise the vote results.
Maduro was widely expected to win the right to complete the new six-year term Chavez won in October, promising to continue oil-funded policies that cut poverty from 50 to 29 percent with popular health, education and food programmes.
Chavez named Maduro, a former bus driver and union activist who rose to foreign minister and vice president, as his political heir in December before undergoing a final round of cancer surgery.
Chavez died on March 5 aged 58.