At least 13 people have been killed and 17 wounded in an explosives attack in western Colombia, a police source told Reuters.

Authorities blamed the violence on dissidents of the FARC rebel group.

The attack took place on the Pan-American Highway in the El Tunel area of Cajibio municipality, about 35 km from Popayan, the capital of Cauca province.

Cauca Governor Octavio Guzman said the attack was one of several criminal actions reported in the province on Saturday.

"Cauca cannot continue to face this barbarity alone. We are facing a terrorist escalation that demands immediate responses," he added.

He also demanded "forceful, sustained and effective action" from the national government in the face of the grave public order crisis.

Calls for action

Presidential candidate Paloma Valencia, a member of the opposition right-wing Democratic Centre party, called the attack "terrorism".

"President Gustavo Petro's government cannot continue minimising the violence or dismantling the state," she said.

"We demand immediate action, full backing for our Armed Forces and police, and concrete results."