The Guatemalan prosecutor's office said Friday elections which yielded a victory for anti-graft candidate Bernardo Arevalo were "null and void," prompting a regional grouping to exhort judicial authorities to desist from an "attempted coup d'etat."
Political outsider Arevalo, who is meant to assume office on January 14, has faced an onslaught of legal challenges since his surprise second-round election victory in August, including attempts to suspend his political party and stop him from taking power.
The 65-year-old's triumph and his pledge to fight graft are widely seen in Guatemala as alarming to the establishment political elite.
On Friday, prosecutor Leonor Morales said investigations have concluded that the election of Arevalo, his vice-president and parliamentarians was "null and void" due to counting "anomalies" in the first round in June.
In Washington, the Organization of American States secretariat in a statement said it "condemns the attempted coup d'etat by the Public Prosecutor's Office of Guatemala."
It added: "the attempt to annul this year's general elections constitutes the worst form of democratic breakdown and the consolidation of a political fraud against the will of the people."
The OAS urged outgoing president Alejandro Giammattei, the constitutional and supreme courts and Congress "to defend the institutions and constitutional order of the country by taking action against the perpetrators of this attack in order to preserve democracy in Guatemala."
Arevalo has denounced an "ongoing coup" by the country's institutions led by Attorney General Consuelo Porras and senior prosecutor Rafael Curruchiche.
Porras, Curruchiche and Judge Fredy Orellana -- who had ordered the suspension of Arevalo's Semilla (Seed) party -- are all on a US list of "corrupt actors."
Curruchiche was present at Friday's press conference, saying "the information that was recorded in the closing and counting act at all polling stations should be annulled."
This "criminal information" would be submitted to the Supreme Electoral Tribunal, he said, for a final decision.
The tribunal has already certified Arevalo's election, but last month it suspended his party for a second time over alleged irregularities with its registration. That investigation is led by Curruchiche.
The moves against Arevalo and Seed has ignited mass protests by Guatemalans demanding the resignation of the three officials.
On Thursday, the president-elect himself led an anti-corruption protest of thousands of people in the capital Guatemala City.
Arevalo pulled off a major upset by advancing to the runoff after a first round marked by apathy among voters.
Poverty, violence and corruption push thousands of Guatemalans abroad every year in search of a better life, many to the United States.
The United States, European Union, UN and Organization of American States have all expressed concern over the events in Guatemala.
The country of 17.6 million is one of Latin America's poorest, with high rates of violent crime.
Rights groups have increasingly expressed concern over what they say are efforts to crack down on prosecutors and journalists in an apparent bid by the government to protect a corrupt system benefiting those in power.
