An oil pipeline has been blown up in south-western Colombia.
Local officials are blaming the Farc rebel group for the attack.
It happened near the city of Tumaco, which has been without power for the past 10 days following an earlier rebel attack on its electricity grid.
Officials say the repairs have been slowed down by rebels booby-trapping the area, which led to the killing of two electricity workers and an indigenous guide on Wednesday.
Police said the attack on the Transandean oil pipeline happened in the early hours of Sunday.
Colombia’s state oil company Ecopetrol said the attack had forced it to stop pumping oil through the 300km (185-mile) pipeline leading from neighbouring Ecuador to the port city of Tumaco.
The Ministry of Defence said attacks on Colombia’s oil industry had increased this year, with 67 incidents between January and June 2012, compared to 84 for all of 2011.
Residents of Tumaco, a port city, took to the streets on Saturday to protest against the rise in attacks.
Local businesspeople said they had suffered severe losses in trade since eight electricity pylons were destroyed 10 days ago.
Last month, Farc rebels blew up a bridge in Caqueta province, leaving the local population cut off
Tumaco mayor Victor Gallo had called for the march to show the town’s desire for peace.
“We don’t know why our town has been hit by this wave of violence, and we don’t know what to do to combat it,” he said.
Local electricity company CEDENAR said it did not know when power could be restored to Tumaco.
Two of its repair men and an indigenous guide the company had hired died when they stepped on a landmine near one of the targeted pylons on Wednesday.
In recent years, Colombian government forces have had considerable success against the Farc in the decades-long civil conflict.
Head of the Armed Forces Gen Alejandro Navas said the increase in attacks on infrastructure such as pipelines and bridges was a last-ditch attempt by the rebels to make their presence felt.
“When the sow squeals, it’s because the noose around its neck is tightening,” he said last week.