At least 80 people are dead and more than 18,000 have been forced to flee their homes in Colombia, officials say, amid fierce clashes between two rival armed groups on the border with Venezuela.

At least 20 Colombian fighters from rival rebel factions were killed in weekend clashes over control of a strategic jungle area for drug trafficking, military sources and the human rights ombudsman office reported on Monday.

The unusually deadly violence delivers a devastating blow to the “total peace” program of the country’s first leftist president, Gustavo Petro.

Colombia vowed "war" against left-wing guerrillas Monday, as security forces rushed to contain a wave of violence that has killed more than 100 people and threatens to derail the country's

A fresh outbreak of guerrilla violence amid a faltering peace process in Colombia has left more than 80 people dead, including civilians, and displaced around 11,000 in just four days,