Guerrillas are active in the Colombian provinces of Arauca and Norte de Santander.

ECONOMIST: Venezuela

The statement came three weeks after the ELN kidnapped a group of employees of an international mining firm, also in Norte de Santander province.

BBC: Colombia ELN kidnap victims are German pensioners

Oil has become a problem for indigenous communities such as the U'Wa, who live in the eastern provinces of Arauca, Casanare, Santander, Norte de Santander and Boyaca.

BBC: Colombia's indigenous peoples face uncertain future