Even as thousands of soldiers rushed to quell violence near the northeastern border with Venezuela -- where more than 80 have been killed and 11,000 displaced by days of fighting -- the defense ministry reported a similar outbreak of fighting in a remote Amazon region.

A ministry official told AFP that 20 people had been killed in fighting between rival left-wing guerillas in Guaviare department.

The Amazon clashes involved rival FARC splinter groups -- leftwing guerillas who, unlike the rump Revolutionary Armed Forces of Colombia, have not signed peace accords.

The violence is a fresh challenge for Colombia's leftist president Gustavo Petro who has staked his political fortunes on a policy of "total peace."

In the face of some public opposition, Petro launched negotiations with the various hardline armed groups that still control parts of Colombia after being elected in 2022.

Critics allege that his conciliatory approach has emboldened groups who are often funded by the proceeds of cocaine and other trafficking, and allowed them space to grow in power and influence.

A 2016 peace deal with FARC was hailed as a turning point in the six-decade-long conflict between Colombian security forces, guerrillas, right-wing paramilitaries and drug gangs, which has left nearly half a million people dead.

But dissident factions continue to control territory in several parts of Colombia, the world's biggest cocaine producer.