Colombia accused the leftist FARC guerrilla group Tuesday of plotting to kill former president Alvaro Uribe, a vehement critic of peace talks with the rebels.
The accusation comes as the present Colombian government is engaged in delicate peace talks with the rebels, and it was not immediately clear what effect it would have on negotiations.
Defense Minister Juan Carlos Pinzon said he had met with Uribe "to inform him of the detection of a plan by the FARC's Teofilo Forero Mobile Column to make an attempt on his life."
Pinzon said President Juan Manuel Santos ordered authorities "to guarantee the security and integrity of the former head of state and protect him, as well as to get those responsible for these threats."
Uribe told reporters in Bogota he would be more careful about his movements in the future, but added: "You have to stay in the fight."
Uribe, 61, waged a fierce war against the FARC during his presidency from 2002 to 2010, reducing Colombia's largest leftist rebel group by half and confining it to remote areas of the country.
After leaving office, he split bitterly with Santos, his former defense minister and successor, for trying to make peace with the rebel group and for mending relations with neighboring Venezuela.
Details of the plot against Uribe were not disclosed, and it was not immediately apparent what impact they might have on the peace talks, which mark their first anniversary on Nov. 19.
The president of the Congress, Juan Fernando Cristo, said the news was "very serious," but reserved judgment on the fallout.
"We have to await the details, what kind of attack or plot was involved. But if it is confirmed, we have to demand that the (FARC) negotiators in Havana explain it to the country," he said.
The Teofilo Forero Column is considered one of the FARC's most active units.
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The Colombian army created a special task force Nov. 1 to go after it and capture its leader, a guerrilla known as "El Paisa" who has a $700,000 bounty on his head.
In May, a judge in Argentina disclosed that a bomb meant for Uribe was found and deactivated in Buenos Aires' Gran Rex theater before he was to give a speech there.
The explosives used in that incident apparently were not very powerful, and Uribe gave his speech at the theater the next day.
In his memoirs, "There is no lost cause," Uribe recalled that FARC rebels killed his father in 1983 during an attempted kidnapping.
Uribe, who lives in his native province of Antioquia, will lead his Central Democratic party's list in elections to the Senate next year.
Santos is expected to run for re-election as president next year, his political fortunes riding on the bid to end the FARC's near 50-year-old insurgency, Latin America's longest.
Santos "has made a political decision: maintain this dialogue with the FARC guerrillas and to endeavor to build a peace accord before Dec. 31," Vice President Garzon said Monday.
Negotiators have reached an agreement on only two of five agenda points in peace talks in Havana talks.
They agreed just last week on the second agenda point — a framework for the rebels' political participation once the near 50-year-old conflict ends.
They have also reached consensus on a common approach to land reform and rural development, issues at the root of the conflict.
But they must still find common ground on three other issues: drug trafficking, reparations for victims of the conflict, and disarmament.