12 killed after leftist rebels ambush group transporting Colombian election ballots

Voters walk inside a polling station during local and regional elections in Bogota, Colombia, on Sunday, Oct. 25, 2015 (AP Photo/Fernando Vergara)

BOGOTA -- Leftist rebels on Monday ambushed poll workers transporting ballots cast at an indigenous reservation in Colombia's regional elections, killing 12 security forces members who were protecting the group.

Authorities attributed the attack in the Andean highlands to the National Liberation Army, the country's second-biggest rebel group.

Of those killed, 11 belonged to the army while the other was a police officer. Six more people remained missing, including two poll workers and an indigenous guide, Defence Minister Luis Carlos Villegas said.

Villegas said the group had been transporting 130 ballots to the capital for tallying. They had been cast on Sunday by residents of an U'wa Indian reservation on the edge of the popular Sierra Nevada del Cocuy national park.

"They were safeguarding the political liberty of our U'wa brothers," Villegas said in a press conference, adding that the military's top command had travelled to the area to oversee efforts to locate those still missing as well as the attackers.

The National Liberation Army, or ELN, is Colombia's second-largest rebel group. The Cuban-inspired group has been holding exploratory peace talks with government representatives for more than a year but so has refused to join the more powerful Revolutionary Armed Forces of Colombia in initiating formal talks aimed at ending a half century of bloodshed.

President Juan Manuel Santos expressed his condolences saying the attack marred what had otherwise been the safest elections Colombia has held in decades, with a 60 per cent reduction in violence compared with the previous vote in 2011.