It comes after former FARC commanders Ivan Marquez and Jesus Santrich announced on YouTube that they were going to take up arms again.
Nine members of the former Revolutionary Armed Forces of Colombia (FARC) have been killed in a bombing raid in southern Colombia, the government has said.
It comes after former FARC commanders Ivan Marquez and Jesus Santrich in announced in a YouTube video on Thursday that they were going to take up arms again and resume fighting the government, saying the 2016 peace accords have been betrayed.
The announcement was condemned by the government, the United Nations and the FARC political party, whose leadership said the majority of ex-rebels remain committed to peace despite "difficulties and dangers."
The bombing took place in the municipality of San Vicente del Caguan, in the jungle province of Caqueta, President Ivan Duque said.
"Thanks to strategic, meticulous, impeccable and rigorous work, Gildardo Cucho, a leader in this organization, was killed," Duque told journalists in the city of Sincelejo.
"This criminal was dedicated to drug trafficking, kidnapping, the intimidation of social leaders and he was expected to be part of this threatening new group which yesterday presented itself to the country as a new rebel group - which it isn't because it's a narco-terrorist gang," he added.
Dissidents from FARC include some guerrillas who refused outright to demobilize under the peace deal and others who initially backed the process before returning to fight.
More than 260,000 people have been killed and millions displaced during Colombia's decades-long conflict between the government, rebel groups, crime gangs and right-wing paramilitaries.
Dissident forces are estimated to number more than 2,200.
Many are thought to be based in Venezuela, where President Nicolas Maduro has said former rebels commanders were welcome.