Colombian state-run oil company Ecopetrol SA said a bomb attack on the Trasandino pipeline late Monday near a populated area caused a fire but no injuries.
The bombing hit the pipeline near the town of El Pailon in Narino Province, close to the border with Ecuador, the company said Tuesday, adding that the fire has been contained.
The pipeline was not operating at the time of the attack, the third this year. There were 16 attacks on the pipeline in 2018.
Ecopetrol did not say who was responsible but security sources attributed it to the National Liberation Army (ELN) rebel group, which frequently attacks oil and energy infrastructure in the area.
The company said it is waiting for security forces to secure the area so it can assess the damage.
The 306-km (190-mile) Trasandino pipeline has capacity to transport about 85,000 barrels of crude daily from fields in Putumayo Province to the Pacific Ocean port of Tumaco, where it is exported.