TEGUCIGALPA, Honduras -- President Juan Orlando Hernandez has been declared the winner of Honduras' disputed election, but that did little to quell unrest from weeks of uncertainty as new protests erupted Monday and the Organization of American States proposed a re-do of the vote.

The OAS, which had sent election observers to the country, issued a statement saying it was impossible to determine the outcome with enough certainty due to irregularities including "deliberate human intrusions into the computer system, intentional elimination of digital traces," opened ballot boxes and "extreme statistical improbability regarding levels of participation within the same department," combined with the narrow vote differential.

"The only possible path for the winner to be the Honduran people is a new call for general elections. ... Respecting democratic values and citizens is the necessary road to safeguard society from death and violence," the OAS said.

Supporters of challenger Salvador Nasralla blocked streets and highways around the country Monday with burning tires and rocks. As soon as police and soldiers would clear the obstacles, protesters would put them back.

Universities, banks and some other businesses remained closed due to the disturbances in Tegucigalpa. Those who still had to work made their commutes on foot.

Most businesses were closed in the country's second city, San Pedro Sula. National Police spokesman Jairo Meza said some businesses there had been looted.

Textile magnate Adolfo Facusse, not a supporter of the president, said people were frustrated by an electoral court that favoured Hernandez.

"We must have new elections," he said. "That is a good decision, but President Hernandez will have to give in to the public."

A bus was burned near La Lima about 185 miles (300 kilometres) north of Tegucigalpa.

"It's better to be locked up in our houses," said Maria Velasquez, a teacher living in Valle de Angeles, a town outside the capital.

Maria Gutierrez, a street vendor blocking the entrance to the Kennedy neighbourhood in south Tegucigalpa with dozens of others, said she just wants Hernandez gone.

"We're not fighting for Nasralla or anyone," she said. "We fight for our rights."

At least 17 people have died in violent street clashes since the Nov. 26 vote.

Electoral tribunal president David Matamoros announced Sunday evening that Hernandez had won the election, saying, "We have fulfilled our obligation (and) we wish for there to be peace in our country."

According to the court's official count, Hernandez won with 42.95 per cent to 41.42 for Nasralla, who well before the announcement had challenged the result and said he would not recognize it.

There was no immediate public comment by Hernandez, whose sister Hilda Hernandez, a Cabinet minister, died Saturday in a helicopter crash.

The first results reported by the electoral court before dawn the day after the election showed Nasralla with a significant lead over Hernandez with nearly 60 per cent of the vote counted.

But public updates of the count mysteriously stopped for more than a day, and when they resumed, Nasralla's lead steadily eroded and ultimately reversed in Hernandez's favour.

The electoral court recently conducted a recount of ballot boxes that presented irregularities and those whose results were not transmitted the night of the election. It said there was virtually no change to its count.

The OAS decision to call for new elections seemed based in part on an analysis of the vote it requested from Irfan Nooruddin, an elections expert at Georgetown University's foreign service school.

While Hernandez's National Party said his late surge in the count was due to slow-arriving returns from rural areas where Hernandez was stronger, Nooruddin found evidence questioning that explanation.

He said Nasralla's share of the vote began plummeting everywhere -- in his strongholds well as those of the National Party -- at essentially the same point in the vote count.

There were also jumps in turnout in the last third of polling stations to report, increases so dramatic that statistically they would be expected to appear fewer than once in 1,000 replications.

Nooruddin wrote that he can't explain the jump in turnout or the National Party's big gain late in the count. "But put together it is consistent with a hypothesis of tampering with the vote tallies that were counted last."

"I would reject the proposition that the National Party won the election legitimately," he said.

Nasralla travelled to Washington to present what he called numerous examples of evidence of alleged fraud, and he met Monday with OAS Secretary-General Luis Almagro. He said he also planned to meet with officials from the U.S. State Department and human rights groups.

"The United States looks at us like a very small country," Nasralla said in Washington. They have bigger problems in the context of world politics and because of that does not give enough importance to what we want."

Interviewed by UneTV during a layover earlier at the Miami airport, Nasralla called Hernandez's re-election illegitimate and said he would ask the OAS to invoke its democratic charter against Honduras.

"The declaration by the court is a mockery because it tramples the will of the people," Nasralla said.

Former President Manuel Zelaya, a Nasralla ally, called for civil disobedience.

Hernandez, a 49-year-old businessman and former lawmaker, took office in January 2014 and built support largely on a drop in violence in this impoverished Central American country.

But corruption and drug trafficking allegations cast a shadow over his government, and his re-election bid fueled charges that his National Party was seeking to entrench itself in power by getting a court ruling allowing him to seek a second term.

Re-election has long been outlawed in Honduras, and Zelaya was ousted as president in a 2009 coup ostensibly because he wanted to run again himself. He later founded the party that supported Nasralla as its candidate.

Associated Press writers Peter Orsi and Christopher Sherman in Mexico City contributed to this report