Rebel ELN fighters launched attacks in the Catatumbo region, forcing thousands to flee the area.

More than 80 people have been killed in northeastern Colombia in just three days as peace talks with the rebel National Liberation Army (ELN) failed, an official said.

Last Thursday, the ELN launched an attack in the northeastern Catatumbo region against a rival group made up of former members of the now-defunct FARC armed group, which continues to fight after disarming in 2017.

William Villamizal, the governor of Norte Santander province, which includes Catatumbo, said civilians were caught in the middle and an estimated "more than 80 people had died" as of Sunday.

The last deaths on Saturday, estimated at 60 people, including seven former fighters of the Revolutionary Armed Forces of Colombia (FARC), occurred in five cities in the Cocaine Mountains mountains near the Venezuelan border.

The victims included community leader Carmelo Guerrero and seven people seeking to sign the peace agreement, according to a report released late Saturday by a government watchdog.

Thousands of people are fleeing the area, some hiding in nearby dense mountains or seeking help in government shelters.

Villamiza said about two dozen people were injured and about 5,000 displaced by the violence, calling the resulting humanitarian situation "appalling."

"Catatombo needs help," Villamiza said in a public address on Saturday.

"Boys, girls, young men, teenagers, whole families showed up, nothing, on trucks, dump trucks, motorcycles, doing whatever they could, on foot, to avoid becoming victims of this confrontation."

The military said it had sent more than 5,000 troops to the area to "strengthen security."

Army commander Gen. Luis Emilio Cardoso Santamaria said on Saturday that authorities were reinforcing the humanitarian corridor between Tibou and Cucuta to allow safe passage for people forced to flee their homes. He said special urban soldiers were also being deployed to urban capitals where "there are risks and a lot of fear".

The FARC disarmed under a 2016 peace deal after more than half a century of war.

However, the agreement has failed to stamp out violence involving left-wing groups, including FARC die-hards, right-wing paramilitaries and drug cartels, competing for resources and trafficking routes in some parts of the country.

The ELN accuses former FARC rebels of numerous killings in the region, including the Jan. 15 killing of a couple and their 9-month-old baby.

The ELN said in a statement on Saturday that it had warned former FARC members that if they "continue to attack the population ... there will be no alternative but armed confrontation".

In recent days, the ELN has also clashed with the Gulf Cartel, the largest drug cartel in the world's largest producer of cocaine, leaving at least nine people dead in another region of northern Colombia.

The latest violence prompted President Gustavo Petro on Friday to call off talks with the ELN in a bid to seek "comprehensive peace" in the violence-plagued country.