The Honduras opposition said Wednesday they filed an appeal with election officials demanding that President Juan Orlando Hernandez's re-election be annulled because the recent vote was marred by fraud.
Election officials declared Hernandez the victor after narrowly defeating leftist opposition candidate Salvador Nasralla in the controversial November 26 vote.
Nasralla conceded on December 22 shortly after Honduras' key ally Washington endorsed Hernandez's re-election, following a month of deadly street clashes.
Former president Manuel Zelaya, coordinator of the leftist alliance opposed to Hernandez, filed the appeal with the Supreme Electoral Tribunal late Tuesday.
Zelaya, who was ousted in a bloodless coup in 2009, cited "the fraud in the vote counting, the alteration and falsification of precinct vote results" among other irregularities that resulted in Hernandez's triumph over Nasralla, the "legitimate victor."
Early vote returns in the November election showed a strong Nasralla victory, but vote counting then slowed down and took more than a week to complete, with mysterious breaks in the process.
International monitors from both the Organization of American States and the European Union noted irregularities in the process. The OAS said the election process had been of "poor quality" and endorsed opposition calls for a re-election before Nasralla conceded.
According to election officials, the final results showed the conservative Hernandez winning with 42.95 percent of the vote, over Nasralla's 41.42 percent.
After the results were announced, protesters took to the streets where they clashed with police and troops who fired tear gas to try to disperse the demonstrations.
Zelaya's Opposition Alliance Against the Dictatorship said that 34 people were killed in the street clashes, and the United Nations voiced concern over "excessive use of force."
When he conceded last week, Nasralla said that if the United States -- Honduras' biggest trade partner and aid donor -- was siding with his opponent, he had little chance of success.
"With the decision by Washington, I am no longer in the running," he told HCH television station at the time.
The senior US State Department official had told AFP that Washington had not seen "anything that alters the final result that the (electoral authority) has come out with."
Hernandez, 49, stood for re-election against Nasralla, a 64-year-old former TV presenter, despite a constitutional ban on presidents having more than one term.
His conservative National Party said that rule was scrapped by a 2015 Supreme Court ruling.
The coup that ousted the leftist Zelaya in 2009 had been launched ostensibly because of fears he would try to change the constitution and seek a second term in office.