An attack on an army base in the province of Norte de Santander has resulted in the deaths of at least nine Colombian soldiers.
According to the government, rebels belonging to the National Liberation Army (ELN) fired homemade mortar shells at the base in El Carmen.
The assault comes as the public authority and the ELN are participated in harmony talks as a component of President Gustavo Petro's arrangement to bring "complete harmony" to Colombia.
The perpetrators, according to Mr. Petro, were "still absolutely far from peace."
Nine victims were completing their mandatory military service. The attack also caused injuries to eight soldiers.
Since November, the two sides have been holding peace talks, but no bilateral ceasefire has been agreed upon.
The location of the incident is known to be a stronghold of the ELN.The attack, the deadliest since peace talks resumed after a three-year hiatus, is another setback for President Petro's goal of getting all illegal armed groups in Colombia to give up their weapons permanently.
The Gulf Clan, Colombia's main drug cartel, had agreed to a ceasefire with the government last week.
Mr. Petro is Colombia's first left-leaning politician to win the presidency.
Iván Duque, his right-wing predecessor, stopped talking to the ELN after the group detonated a car bomb at a police academy in the capital, Bogotá, in 2019. That explosion resulted in the deaths of 22 people.
Mr Petro has called the public authority designation and underwriter nations engaged with the harmony exchanges for a gathering on Monday, at which they will examine the fate of the harmony interaction.
The attack, one of the most serious in recent months, took place in a rural area of El Carmen municipality in Colombia's Norte de Santander province, an important region for growing coca and producing cocaine.
The government of Colombia's leftist President Gustavo Petro restarted peace talks with the ELN last year as part of a drive for total peace in the Andean country, where almost six decades of internal conflict have left at least 450,000 dead.