Isaac Urrutia / Reuters

Supporters of opposition leader Henrique Capriles take part in a demonstration in Maracaibo on Tuesday to demand a recount of the votes in Sunday's election.

CARACAS, Venezuela – Seven people were killed in violent clashes at opposition protests over Venezuela's disputed presidential election, officials said on Tuesday.

President-elect Nicolas Maduro – the late Hugo Chavez’s hand-picked successor -- said on Tuesday that opposition leaders who called for protests were seeking a coup against his government.

Opposition leader Henrique Capriles has demanded a full recount of votes from Sunday's election after results showed a narrow victory for Maduro.

The election authority has ruled out a recount, raising fears of more violence in the South American nation, which has the world's largest oil reserves.

The deaths happened on Monday when hundreds of protesters took to the streets in various parts of the capital Caracas and other cities, blocking streets, burning tires and fighting with security forces in some cases. Officials also said 135 people were arrested in the post-election violence.

State media and officials said the fatalities included two people shot by opposition sympathizers while celebrating Maduro's victory in a middle-class area of Caracas.

One person died in an attack on a government-run clinic in a central state. Two, including a policeman, were killed in an Andean border state, officials said.

"We will defeat this violent fascism with democracy," said Foreign Minister Elias Jaua, describing incidents and showing video footage to a group of ambassadors. "Those who attempt to take with force what they could not acquire through elections are not democrats."

There was no immediate response from the opposition, and Capriles' camp reiterated demands for peaceful protests on Tuesday as thousands of his supporters marched to regional election offices around the country. The government held counter-demonstrations. 

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Tomas Bravo / Reuters

Venezuelan presidential candidate Nicolas Maduro and his wife Cilia Flores celebrate after the official results gave him a victory in the balloting, in Caracas on Sunday.

News Analysis 

CARACAS, Venezuela -- The late President Hugo Chavez’s hand-picked successor, Nicolas Maduro, narrowly won Venezuela’s presidential election Sunday with just 50.7 percent of the vote, according to election board returns. 

The slim victory over opposition candidate Henrique Capriles, who won 49.1 percent of the vote, was a difference of just about 235,000 votes. 

Capriles has refused to accept the results, alleging incidences of fraud and voting intimidation at polling booths across the country. Instead of a concession speech, the popular 40-year-old governor demanded a recount. "We are talking about a small difference, a tiny difference," he said.  "We will not accept the results until all votes are counted, one by one." 

The Venezuelan government announced that Maduro would be formally proclaimed the winner by the election board at a ceremony and rally in Caracas on Monday afternoon -- despite Capriles' demands for a recount.

While Capriles has not called out for his supporters to take to the streets, a protracted election dispute would be difficult on the deeply divided country.

Whatever the final outcome, the next leader of Venezuela will inherit a country with the world's second largest oil reserves -- but also a nation plagued with problems including food shortages, inflation, corruption and crime. 

Carlos Garcia Rawlins / Reuters

Supporters of Venezuela's opposition presidential candidate Henrique Capriles react after the official results gave a victory to Nicolas Maduro, in Caracas on Sunday.

Empty shelves
"You have to walk all over town from supermarket to supermarket to find what you need," said Olivia Nunez, standing in front of empty shelves at the Magdalena supermarket in Caracas’ Chacao neighborhood. 

Sugar, rice, coffee, milk, cooking oil, chicken and even soap and toilet paper are hard to come by at grocery stores. 

Lifelong residents of the middle-class neighborhood say shortages were unheard of until Chavez took office 14 years ago. When supplies do arrive, neighbors call each other to share the news and rush to stand in lines that sometimes make checkout a two-hour process.

The reasons for the shortages are many. Government measures to enforce price controls have discouraged domestic production. So have government expropriations. Many farm owners hesitate to invest in crops, fearing the fate of neighbors whose land was seized under a Chavez program that grants parcels to low-income families. 

Erika Angulo/ NBC News

This sign tells shoppers in a Caracas grocery store on Sunday that they are restricted to just 4 kilograms of rice per customer.

Adding to the shortages, suppliers of foreign goods say, is the administration's decision to scale back the number of dollars importers can buy. They complain they can't access the necessary dollars to pay manufacturers abroad. 

‘I'm terrified’
Crime is rampant, with kidnappings, robberies and home invasions skyrocketing over the last decade. 

The U.S. State Department has warned travelers that crime in the country is "pervasive, both in the capital, Caracas, and the interior." Violent crimes, including murder, are also up.  Statistics gathered by the nongovernment group Venezuelan Violence Observatory show that for every 100,000 Caracas residents there are 122 murders per year. For comparison, the rate in New York City is 5.6 murders per 100,000 residents. 

Valeria Ardenko said she stopped going out after 8 p.m. after a nephew was mugged at gunpoint. "I used to love to go to the theater, but now I'm terrified," said the 71-year-old grandmother.  

Home invaders who never leave are another risk many Venezuelans face. In some instances, squatters move in while residents are away on vacation. Some 100 activists earlier this month seized dozens of condos and empty lots in Caracas. Police managed to turn back about 16 occupiers, but others remained. 

"We have a government that allows those who have been living in a hut to take over your home because they feel like it. And no one does anything to stop them," said homeowner Aide Solotucha. 

Chavez promoted a process of expropriation of lands and homes deemed unoccupied as a way to deal with the country's home shortage while his administration built public housing.

Still united by oil
Caracas-Washington relations soured during the Chavez regime, with the Venezuelan president frequently accusing the U.S. of interference, even alleging an assassination plot against him. Chavez simultaneously strengthened relations with Iran and Russia, ignoring the concerns of U.S. officials.  And both countries have expelled each other's diplomats.  

But there is still one tie that unites them: oil. 

"The oil trade relationship between Venezuela and the United States has been the source of stability between the two countries during what has been, without question, really rough political and diplomatic times," said Sarah Ladislaw of the Center for Strategic and International Studies in Washington. 

Most energy expert say getting along with whoever ends up being sworn in as this OPEC country's leader will be to the advantage of the U.S. 

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Venezuela awoke to political turmoil Monday after Hugo Chavez's chosen successor, Nicolas Maduro, won the country’s presidential election by such a tight margin that his rival demanded a recount.

The country, already shaken by the death from cancer of its dominating leader, faces uncertainty after Maduro secured 50.7 percent of the votes in Sunday's election, compared with 49.1 percent for Henrique Capriles -- a difference of just 235,000 ballots.

"This is the most delicate moment in the history of 'Chavismo' since 2002," Javier Corrales, a U.S. political scientist and Venezuela expert at Amherst College in Massachusetts, told Reuters, referring to a brief coup against Chavez 11 years ago.

"With these results, the opposition might not concede easily, and Maduro will have a hard time demonstrating to the top leadership of Chavismo that he is a formidable leader."

Capriles refused to recognize the result and said his team had a list of more than 3,000 polling irregularities, Reuters reported.

"This struggle has not ended,” he said. "We are not going to recognize a result until each vote of Venezuelans is counted.”

"I didn't fight against a candidate today, but against the whole abuse of power," said Capriles, the 40-year-old governor of Miranda state. "Mr. Maduro, you were the loser. ... This system is collapsing, it's like a castle of sand -- touch it and it falls."

Officials said Maduro would be formally proclaimed winner at a ceremony and rally in downtown Caracas as early as Monday afternoon, Reuters reported.

For his part, Maduro said he would accept a full recount, even as he insisted his victory was clean and dedicated it to Chavez. 

"We've had a fair, legal and constitutional triumph," Maduro told his victory rally. "To those who didn't vote for us, I call for unity." 

One key Chavista leader expressed dismay over the outcome, The Associated Press reported. National Assembly President Diosdado Cabello, whom many consider Maduro's main rival within their movement, tweeted: "The results oblige us to make a profound self-criticism."

A modest but noisy crowd of Maduro supporters celebrated in Caracas’ Chacao neighborhood, waving flags and setting off fireworks.

A perception that Maduro has a weak mandate could prompt challenges from within the disparate ruling coalition that formed around Chavez, just as overstretched state finances force him to slow the very oil-funded largesse he staked his reputation on maintaining, Reuters said.

The OPEC nation's strong growth is seen by most private economists as dropping this year as the government pares back following hefty spending in 2012 that was a key driver of the economy and helped Chavez win re-election in October, Reuters reported.

However, the New York Times reported that Maduro’s victory could see repairs made to the fractured relationship between Venezuela and the United States.

Bill Richardson, the former governor of New Mexico, who was in Caracas as a representative of the Organization of American States, said in an interview that Maduro called him aside after a meeting of election observers on Saturday and asked him to carry a message, the NYT reported.

“He said, ‘We want to improve the relationship with the U.S., regularize the relationship,’” the newspaper quoted Richardson as saying.

Venezuela's electronic voting system is digital but generates a paper receipt for each vote, making a vote-by-vote recount possible, the AP said. 

Reuters and The Associated Press contributed to this report.

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This story was originally published on Mon Apr 15, 2013 12:01 AM EDT

Luis Acosta / AFP - Getty Images

Venezuela's acting president and presidential candidate Nicolas Maduro gestures during his closing campaign rally in Caracas on April 11, 2013 ahead of Sunday's presidential election.

Raul Arboleda / AFP - Getty Images

Opposition candidate Henrique Capriles attends a campaign rally in Barquisimeto, Lara state, on April 11, 2013.

The late Hugo Chavez's self-declared socialist revolution will be put to the test at a presidential election on Sunday that pits his chosen successor against a younger rival promising change in the nation he polarized.

Most opinion polls give his protege, acting President Nicolas Maduro, a strong lead over opposition challenger Henrique Capriles thanks to Chavez's endorsement and the surge of grief and sympathy over his death from cancer last month.

Ramon Espinosa / AP

Supporters hold a toddler wearing a Maduro-style mustache at the closing campaign rally for Nicolas Maduro in Caracas on April 11, 2013.

Raul Arboleda / AFP - Getty Images

Supporters of Henrique Capriles attend his closing rally in Barquisimeto on April 11, 2013.

Tomas Bravo / Reuters

Nicolas Maduro, left, watches former Argentine soccer star Diego Maradona kick a ball during Maduro's closing rally on April 11, 2013.

The candidates closed out official campaigning on Thursday with dueling rallies, both drawing hundreds of thousands of boisterous supporters. Taking a page out of Chavez's playbook, a fiery Maduro marched through the streets of the capital draped in a Venezuelan flag and called on voters to follow "commander Chavez as the spiritual guide of the fatherland."

"I am the son of Chavez," the burly 50-year-old former bus driver shouted to supporters in downtown Caracas. "I am ready to be your president."

Capriles, an energetic 40-year-old state governor, wrapped up his campaign in the nearby city of Barquisimeto. "Those who govern today have never done anything for your security. Sunday we're going to choose between life and death," he roared to the crowd. "If you want a future, you have to vote for change, for a different government." Read the full story.

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Leo Ramirez / AFP - Getty Images

Capriles pours water on his head during his final rally on April 11, 2013.

Enric Marti / AP

A soldier looks through binoculars at people gathered along Bolivar Avenue for the closing campaign rally for ruling party presidential candidate Nicolas Maduro in Caracas on April 11, 2013.