Soldiers patrol in Tegucigalpa, a day before Sunday's presidential vote. (Rodrigo Abd/Associated Press)

Ruling party candidate Elvin Santos has conceded defeat to conservative rancher Porfirio Lobo in post-coup Honduran elections.

Santos says it is time for "unity, the only path to confront the future and ensure the victor of all Hondurans."

Preliminary official results showed Porfirio Lobo, of the opposition National Party, with 56 per cent support with more than 60 per cent of the tally sheets counted.

Perhaps more importantly, election officials said more than 60 percent of registered voters cast ballots Sunday, a victory for interim leaders who hoped a large turnout would bolster the vote's legitimacy in the eyes of the world.

The election comes five months after a coup ousted Manuel Zelaya. Neither Zelaya nor Roberto Micheletti, the military-backed leader who replaced him, had their names on the ballot.

Zelaya watched from the sidelines at the Brazilian embassy in the Honduran capital, Tegucigalpa, where he has been since he secretly returned to the country in September.

After polls closed early Sunday evening, Zelaya claimed in a statement that he had information from 1,400 polling stations indicating that abstention was as high as 65 per cent.

"As president of Honduras I declare this process illegitimate," he said.

Electoral official Denis Gomez, however, said he thought turnout was about 70 per cent, although it was not an official projection.

Honduran soldiers had been out in force all week leading up to the election. About 30,000 troops have been deployed to keep the peace after Zelaya called for a boycott of the vote.

"Abstention will defeat the dictatorship," Zelaya told Radio Globo from the embassy.

The army has been a fixture on the streets since soldiers rousted Zelaya from his bed on June 28 and forced him into exile at gunpoint.

The de facto government has suspended civil liberties, silenced opposition broadcasters and sent police and soldiers into the streets to face off with protesters.

Opinion polls indicated Lobo was the frontrunner.

Lobo and Santos, both wealthy businessmen from the political old guard, signed a pledge to honour the constitutional ban on running for re-election.

The political crisis stemmed from Zelaya's plan to hold a referendum that could have changed the constitution to allow longer terms for the president.

The United States says it will accept the results of the vote, but most Latin American countries, led by Brazil, say they won't recognize a coup-backed government.

Canada is somewhere in between. Minister of State for Foreign Affairs Peter Kent says holding a "successful election by itself will not bring Honduras back to democratic legitimacy."

In August, Kent was named by the Organization of American States as part of a delegation of foreign ministers that had been trying to persuade the interim government to reinstate Zelaya as president.

With files from The Associated Press