TEGUCIGALPA, Dec. 18 (Xinhua) -- Official election results that verified the incumbent's win fueled protests on Monday in Honduras, where supporters of the opposition were contesting the results and calling for new elections to be held.

Nearly a month after the Nov. 26 elections, the Supreme Electoral Court (TSE) on Sunday said the outcome was official: the candidate of the Opposition Alliance, Salvador Nasralla, was defeated by President Juan Orlando Hernandez's bid for reelection.

The announcement led the head of the alliance, former president Manuel Zelaya, to call on followers to continue to take to the streets to demand a recall.

"We are calling for the immediate and definitive mobilization of the Honduran people... to defeat electoral fraud," Zelaya said at a press conference.

Protesters set fire to tires and blocked roadways, clashing with military troops deployed to clear the avenues using tear gas. There was some looting, especially in San Pedro Sula, the second-largest city after the capital Tegucigalpa.

On Monday, Nasralla met in Washington, D.C. with the secretary general of the Organization of American States (OAS), Luis Almagro, to denounce the alleged electoral fraud.

The OAS, which had international observers monitoring the polls, has made its own announcement, acknowledging the elections were marred by irregularities and proposing a new round of voting.

"OAS General Secretariat proposes new elections in Honduras after the 2nd report of (the) Observation Mission," the organization posted to Twitter.

The head of the European Union Observer Mission at the elections, Marisa Matias, said via Twitter that "only Honduran institutions have the power to make decisions about the electoral process."

Meanwhile, several Latin American leaders, including Colombia's President Juan Manuel Santos, already congratulated Hernandez for winning a second four-year term.