More than 80 people have been killed in just three days in northeast Colombia following failed attempts to hold peace talks with the rebel National Liberation Army (ELN), an official has said.

The ELN launched an assault in the northeastern Catatumbo region last Thursday on a rival group comprised of ex-members of the now-defunct FARC armed group who kept fighting after it disarmed in 2017. Civilians were trapped in the middle, and by Sunday, it was estimated that "more than 80 people have lost their lives,” said Governor William Villamizar of the Norte de Santander department that includes Catatumbo.

The last toll on Saturday was estimated at 60 people, including seven former fighters from the Revolutionary Armed Forces of Colombia (FARC), in five municipalities of the mountainous cocaine-producing region near the border with Venezuela. Among the victims are community leader Carmelo Guerrero and seven people who sought to sign a peace deal, according to a report that a government ombudsman agency released late on Saturday.

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

Villamizar said about two dozen people had been injured and some 5,000 displaced in the outbreak of violence, and described the resulting humanitarian situation as "alarming”.

"Catatumbo needs help,” Villamizar said in a public address on Saturday.

"Boys, girls, young people, teenagers, entire families are showing up with nothing, riding trucks, dump trucks, motorcycles, whatever they can, on foot, to avoid being victims of this confrontation.” The army said more than 5,000 soldiers have been sent to the region to "reinforce security”.

Army commander General Luis Emilio Cardozo Santamaria said on Saturday that authorities were reinforcing a humanitarian corridor between Tibu and Cucuta for the safe passage of those forced to flee their homes.(Agencies)