TEGUCIGALPA, Nov 28, 2013 (AFP) - The head of Honduras' electoral tribunal on Wednesday declared conservative Juan Orlando Hernandez the winner of the presidential poll, amid allegations of vote-rigging from the losing leftist candidate.

"These numbers that we released today clearly indicate that the winner of the general election is Juan Orlando Hernandez," said Mr David Matamoros, president of the Supreme Electoral Tribunal, on radio and television.

Figures from 81.5 per cent of polling stations give Mr Hernandez 35.88 per cent to Ms Xiomara Castro's 29.14 per cent.

"In the coming days, we will issue the official declaration, once we have added the records that are needed," he added.

The electoral tribunal had already said Mr Hernandez's lead was irreversible given the number of votes remaining to be counted.

But Ms Castro's campaign accuses the Supreme Electoral Tribunal of manipulating 19 per cent of the votes to favor Mr Hernandez and plans to call massive street protests over the alleged fraud.

"On Saturday, we are going to summon people to protest. The Libre (Party) and Xiomara (Castro) have been robbed of their victory, and we are going to show it," her husband, ousted former president Manuel Zelaya, told Radio and TV Globo.

"For now, we do not recognize the results" that have been given, Mr Zelaya said, insisting that they had been "manipulated, and we are going to prove it".

European Union and Organisation of American States observers called the voting process transparent and non-problematic.

"We will defend the will of the people as it was expressed at the polls," Ms Castro wrote in a Twitter posting late on Tuesday.

Mr Zelaya, meanwhile, said in a post that "we will confirm our victory". A civil society group GSC issued a plea for the electoral authorities to "answer to the fraud charges immediately". Tensions were running high as the political stand-off again spread to the streets with protests by students.

"No to fraud!" they shouted during a demonstration in support of Ms Castro outside the gates of a university east of Tegucigalpa.

On Tuesday, about 100 police in helmets and riot gear used tear gas and then truncheons to beat 800 pro-Castro protesters and send them scrambling.

Mr Hernandez is a law-and-order conservative who has promised a militarized program to improve public safety in the nation with the world's highest murder rate, which is also among the poorest in Latin America.

Gangs run whole neighborhoods, extorting businesses as large as factories and as small as tortilla stands, while drug cartels use Honduras as a transfer point for shipping illegal drugs, especially cocaine, from South America to the United States.

The clash between Mr Hernandez, of the National Party, and Ms Castro, of the Libre party, brought new uncertainty to a deeply troubled country, also reeling from the wounds of the coup just four years ago.

Mr Hernandez, who is also Speaker of the legislature, said the people have spoken at the ballot box.

The governments of Colombia, Guatemala, Panama and Costa Rica congratulated Mr Hernandez. Nicaragua's leftist President Daniel Ortega also recognized Mr Hernandez as the winner.

The election's winner will inherit a country of 8.5 million people with 71 per cent of the population living in poverty and a soaring homicide rate of 20 murders per day.

Ms Castro, who proposes "Honduran-style democratic socialism", wants to rewrite the Constitution and "re-found" the country - a move similar to the one that led to the coup that ousted her husband in 2009.

Mr Zelaya was elected Honduran president as a PL candidate in 2005.

But when he moved to the political left and tried to reform the Constitution, the military abruptly deposed him with support from Congress and the Supreme Court.