Many of the victims were women and children sleeping when the explosion ripped apart a section of the 500-mile-long (800km) Ocensa pipeline near the gold-mining villages of Machuca and Fraguas in northwest Antioquia Province.
Police blamed the blast on the National Liberation Army (ELN), Colombia's second-largest guerrilla group, which only last week started tentative peace talks with the government and independent civic leaders. The incident is likely to be a severe embarrassment to the ELN as it strives to portray itself as a political as well as military movement. It also risks torpedoing the talks to end Colombia's long-running civil conflict, which has claimed at least 35,000 lives in the past decade.
"Survivors say the guerrillas arrived and blew up the pipeline, which caused an explosion, spilt crude and set the whole village alight," Jairo Guerra, a police agent, said.
The Ocensa pipeline is owned and operated by a private British, French and Canadian consortium. The pipeline, which had been pumping about 350,000 barrels of crude per day, serves the Cusiana-Cupiagua complex, which is operated by British Petroleum, in the eastern plains region.