BOGOTA – Colombian President Juan Manuel Santos hoped the bilateral ceasefire with the National Liberation Army, starting Oct. 1, would lead the guerrillas to surrender their weapons like the Revolutionary Armed Forces of Colombia.

“It is a very important step, a step that I hope will be the first step in a process that also leads the ELN to drop weapons, as happened with the Revolutionary Armed Forces of Colombia (FARC),” Santos said on Thursday at the National Museum during the inauguration ceremony of a photo exhibition.

“At this moment we are finalizing the last protocol to be able to begin the ceasefire with the National Liberation Army (ELN) from Oct. 1,” Santos was quoted as saying in a statement released by his office.

Santos’s statement comes amid a series of attacks by ELN on the country’s oil infrastructure that led to financial losses worth millions and contaminated rivers and streams, especially in the departments of Norte de Santander and Arauca, bordering Venezuela.

The Colombian government’s negotiating head at the peace talks with the ELN, Juan Camilo Restrepo, said on Friday the oil spill caused by a guerrilla attack on the Caño Limon-Covenas oil pipeline could contaminate Lake Maracaibo in Venezuela.

Colombia’s state-owned oil company Ecopetrol denounced on Thursday the attack on a pipeline in the northeast of the country.

The affected pipeline transports fuel from Caño Limon in Arauca (northeast), to Covenas in Sucre (north), in the Caribbean Sea.

The oil company says there have been 46 attacks, including that on Thursday, on the crude oil transport system so far.

On Sept. 4, Santos had announced the bilateral ceasefire agreement which, according to Restrepo, is the first peace document to be signed with the ELN in 50 years.

The agreement was sealed in Quito and will be valid initially for 102 days, until Jan. 12, 2018.