A bombardment by government forces killed 23 dissident members of the demobilised Revolutionary Armed Forces of Colombia, or FARC, including commander Jorge Eliecer Jimenez, known as Arturo.
At least 23 dissidents of the former FARC guerrilla group were killed during an operation by the Colombian armed forces along the Venezuelan border.
The dissidents "died during military operations" carried out in the northern border department of Arauca, a source in the Defense Ministry told AFP news agency on Thursday.
Five dissidents were additionally injured, the source said.
Among the dead was a former leader of the Revolutionary Armed Forces of Colombia (FARC), known as "Arturo."
Colombian Defense Minister Diego Molano said Arturo "took refuge in Venezuela and from there sought to reactivate the dissident groups to continue committing crimes."
"This operation forcefully dismantles the FARC dissident structure," said Molano in a video published to social media.
Another rebel group leader known as "Ernesto" was also killed in the operation, which adds to a recent string of successful military offensives.
Military planes and helicopters took part in the bombardment in the municipality of Puerto Rondon, according to Molano.
Arauca is a narcotrafficking corridor that has seen fierce fighting between armed groups since the beginning of the year.
Former FARC dissidents, as well as members of Columbia's last active guerilla group known as the ELN, have set up bases in Venezuela.
Colombian authorities say they receive government backing in Venezuela — an accusation Caracas denies.
Last month, the president announced the "neutralisation" of the rebel group leader known as "Jhonier," while in October of last year the drug kingpin known as "Otoniel" was captured.
He is now awaiting extradition to the United States.