The Colombian army killed at least 13 leftist guerrillas early Wednesday in two separate engagements, Defense Minister Juan Carlos Pinzon said.

Eight ELN guerrillas were killed in an operation in the eastern province of Arauca and at least five fighters from the FARC guerrilla group were killed in the central province of Meta, said Pinzon, labelling the rebels "terrorists."

"A terrorist presence was detected in these areas trying to attack highways or infrastructure, so the armed forces acted," he told journalists.

He said the toll could rise as troops continue sweeping the two areas.

The army said in a statement that the operation in Arauca, which also involved the air force, navy and national police, targeted an ELN camp that was "responsible for attacks on civilians, roads and oil infrastructure in recent days."

Eight ELN fighters were captured in the operation, including several minors who have been handed over to child protection authorities, it said.

One wounded guerrilla was captured in Meta.

The defense minister is expected to travel to the Arauca region, which borders Venezuela, later Wednesday.

The latest fighting comes 10 days after another operation that killed 14 FARC guerrillas in the northwestern region of Antioquia.

The Colombian government and FARC have been holding talks in Cuba since November 2012 aimed at ending the 50-year-old conflict, but no ceasefire has been declared.

President Juan Manuel Santos won re-election last month after campaigning largely on his promise to bring the peace process to fruition.

Santos, who begins his new four-year term on August 7, has also opened preliminary talks with the ELN.

According to the government, FARC (Revolutionary Armed Forces of Colombia) has between 7,000 and 8,000 fighters, while the ELN (National Liberation Army) has about 2,500.

The conflict in Colombia has killed more than 220,000 people and caused more than five million to flee their homes since the ELN and FARC were founded in the 1960s.

Besides the army and guerrillas, it has drawn in rightwing paramilitary groups and drug gangs.