Bogotá, Colombia (AFP) — Rebels in Colombia who have launched an armed strike have essentially trapped thousands of people in the northwest, authorities said.

Around 9,800 people have been forced to confine themselves due to the "indefinite armed strike" imposed in Choco department by the ELN guerrillas amid congoing peace negotiations with the government, the Ombudsman's Office reported.

"Following the announcement of an armed strike" by the rebels in the department of Choco, "at least 9,800 people from the municipalities of Istmina, Medio San Juan, Sipi and Novita" are "in indefinite confinement," with restrictions on "mobility," "daily activities," "transportation of groceries and food as well as access to health services," the ombudsman's office said in a statement.

In a document released on Wednesday, the National Liberation Army prohibited circulation and activity in that region, alleging the murder on Monday of "young Santiago Caceres" at the hands of "paramilitaries" in "collusion" with government forces.

The "armed strike" has drawn criticism both from the opposition and from the leftist government, which earlier this week said it had successfully concluded the first cycle of peace talks with the guerrillas in Caracas.

At the end of the round of talks, the government and the ELN announced "humanitarian actions" to mitigate the violence precisely in the area where the rebels are now paralyzing activity under threat.

Colombia has suffered more than half a century of armed conflict between the state and various groups of left-wing guerrillas, right-wing paramilitaries and drug traffickers.

The ELN is the last recognized rebel group operating in Colombia, although FARC dissidents who refused to sign the 2016 peace deal remain active.

The parties in November resumed the peace process that had been suspended under the former government of President Iván Duque.

Armed since 1964, the ELN has a force of some 2,500 fighters and a wide network of collaborators, according to independent estimates.