The leader of the last active guerrilla group in Colombia, Nicolas Rodriguez Bautista, has announced his retirement due to ill health, eliciting an angry response from Bogota.

Bautista, alias "Gabino," has been in command of the National Liberation Army (ELN) since 1998, having joined the rebels at age 14.

Now 71, Bautista announced his retirement from an undisclosed destination in Cuba in a statement dated May 1 but distributed by the ELN on Thursday.

He said he has been in Cuba since May 2018 under a humanitarian agreement between the two countries, and is receiving medical care there for an undisclosed ailment.

Reacting to the announcement, Colombia's High Commissioner for Peace Juan Camilo Restrepo, said it was not news of Bautista's resignation the world was awaiting, but "the ELN's renouncement of its criminal actions" which include recruiting minors, kidnappings, and planting anti-personnel mines.

In another statement, dated June 14 but also released Thursday, the ELN said Bautista would be replaced by Antonio Garcia.

Handout picture released on July 28, 2011 by the Ministry of Defense with Nicolas Rodriguez Bautista a.k.a. "Gabino" second from right. AFP PHOTO/Ministerio de Defensa Nacional/HO
Handout picture released on July 28, 2011 by the Ministry of Defense with Nicolas Rodriguez Bautista a.k.a. "Gabino" second from right. AFP PHOTO/Ministerio de Defensa Nacional/HO Ministerio de Defensa Nacional / HO

Colombian President Ivan Duque ended negotiations in 2019 with the ELN, the only rebel force still active after a 2016 peace accord disarmed the last guerrillas of the FARC to end decades of civil war.

He called off talks after a car bomb attack claimed by the ELN killed 22 police cadets.

Duque wants Cuba to hand over ELN members who are on its soil.

Colombia is in the midst of its worst outbreak of violence since the 2016 peace deal that ended Latin America's most powerful insurgency, having claimed more than nine million victims between the dead, missing and displaced.

Armed groups, including dissident FARC members who turned their backs on the peace pact, continue fighting for territory and resources, including drug fields and smuggling routes.