Colombia's military killed nine militants in a bombing near the Venezuelan border, a defence ministry source told AFP on Friday.
The operation, which took place in Arauca province, was part of President Gustavo Petro's intensifying crackdown on rebels involved in cocaine trafficking.
Local media reported that authorities are investigating whether the strike killed Antonio Medina, a high-ranking rebel commander responsible for a bloody war between ex-FARC fighters and the National Liberation Army (ELN) guerrilla group.
The Colombian military had this week carried out air strikes in the Amazon region, killing 19 members of an ex-FARC splinter group.
Colombia's president had been facing pre-election criticism and US sanctions for his alleged reluctance to target armed cocaine-trafficking groups.
In October, Washington slapped unprecedented sanctions on Petro, his wife, son, and a top aide, accusing them of enabling drug cartels.
The US government provided no evidence linking Petro directly to drug trafficking.
Petro had previously opted to engage well-armed cocaine-producing groups in talks, rather than conduct open warfare, since he took power in 2022.
He is constitutionally barred from running for president again.
