Shortly after the National Electoral Council, which is loyal to Maduro's ruling party, announced he had won a third six-year term, angry protesters began marching through the capital and cities across Venezuela.
In Caracas, the protests were mostly peaceful, but a brawl broke out when dozens of riot gear-clad police blocked the caravan in an upper-class district.
A brawl broke out in Caracas when dozens of riot gear-clad police blocked a caravan of protesters. (AP PHOTO)
Police used tear gas to disperse the protesters, some of whom threw stones and other objects at officers.
In the capital's impoverished Petare neighbourhood, some protesters shouted,"It's going to fall. It's going to fall. This government is going fall!" as they walked.
The street protests followed earlier "cacerolazo" demonstrations - a traditional Latin American protest in which people bang pots and pans - throughout the country.
The demonstrations came after an election on Sunday that reflected hopes Venezuela could avoid bloodshed and end 25 years of single-party rule.
The winner was to take control of an economy recovering from collapse and a population desperate for change.
"We have never been moved by hatred. On the contrary, we have always been victims of the powerful," Maduro said in a televised ceremony.
"An attempt is being made to impose a coup d'etat in Venezuela again of a fascist and counter-revolutionary nature," he added, saying that Venezuela's "law will be respected".
There was no immediate comment from the opposition, which had vowed to defend its votes.
Venezuelan protesters banged on pots and pans during traditional "cacerolazo" demonstrations. (AP PHOTO)
Opposition leaders planned to hold a news conference later in the day.
Officials delayed the release of detailed vote tallies from Sunday's election after proclaiming Maduro the winner with 51 per cent of the vote, compared with 44 per cent for retired diplomat Edmundo Gonzalez.
The competing claims set up a high-stakes stand-off.
"Venezuelans and the entire world know what happened," Gonzalez said, but he and his allies asked supporters to remain calm and called on the government to avoid stoking conflict.
Several foreign governments, including the US and the European Union, held off recognising the election results.
After failing to oust Maduro during three rounds of demonstrations since 2014, the opposition put its faith in the ballot box.
The country sits atop the world's largest oil reserves and once boasted Latin America's most advanced economy.
But after Maduro took the helm, it tumbled into a free fall marked by plummeting oil prices, widespread shortages of basic goods and hyperinflation.
President Nicolas Maduro warned that Venezuela's "law will be respected" as he claimed victory. (AP PHOTO)
US oil sanctions sought to force Maduro from power after his 2018 re-election, which dozens of countries condemned as illegitimate.
But the sanctions only accelerated the exodus of some 7.7 million Venezuelans who have fled their crisis-stricken nation.
The official results came as a shock to many who had celebrated what they believed was a landslide victory for Gonzalez.
Gabriel Boric, the leftist leader of Chile, called the results "difficult to believe", while US Secretary of State Antony Blinken said Washington had "serious concerns" the announced tally did not reflect the actual votes or the will of the people.
Opposition leader Maria Corina Machado said the margin of Gonzalez's victory was "overwhelming", based on tallies the campaign received from polling booths.
Gonzalez, 74, was unknown until he was tapped in April as a last-minute stand-in for opposition powerhouse Machado, who was blocked by the Maduro-controlled supreme court from running for any office for 15 years.
Authorities set the election to coincide with what would have been the 70th birthday of former president Hugo Chavez, the revered left-wing populist who died of cancer in 2013, leaving his revolution in the hands of Maduro.
But Maduro and his United Socialist Party are more unpopular than ever among many voters who blame his policies that spurred hunger, crippled the oil industry and separated families due to migration.
