BOGOTA -- 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 clashes pitted opposing factions from what was once the Revolutionary Armed Forces of Colombia (FARC) against one another in the country's southeastern Guaviare jungle.

The violence follows an offensive launched by another rebel group, the National Liberation Army (ELN), in northeastern Catatumbo region that left at least 80 people dead and 11,000 displaced.

In a social-media post, President Gustavo Petro declared a state of "internal unrest and economic emergency" in the Catatumbo area and accused the warring factions of having "lost their heads."

"A high number of people have been reported dead and injured," the ombudsman's office wrote on social media, referring to the weekend's clashes. The army and local authorities reported at least 20 dead rebels in the latest jungle violence.

The rival FARC factions include one that is engaging in peace talks with Petro's administration, and another that has vowed to fight on after the government suspended a bilateral ceasefire.

The two factions split last April due to internal differences.

Armed conflict in Colombia has lasted more than six decades and is funded mainly by drug trafficking and illegal mining. It has left over 450,000 dead and millions displaced.