Two leftist FARC guerrillas were killed Monday in a flare-up of fighting in Colombia that claimed the lives of 25 soldiers and rebels over the weekend, the military said.

Two leftist FARC guerrillas were killed Monday in a flare-up of fighting in Colombia that claimed the lives of 25 soldiers and rebels over the weekend, the military said.

The latest casualties occurred during combat in the southwestern region of Cauca between an elite army task force and A FARC unit.

The FARC, a Spanish acronym for the Revolutionary Armed Forces of Colombia, has been engaged in peace talks with the government since November.

But despite recent optimism over the progress in the talks, fighting heated up over the weekend in various parts of the country.

On Saturday, six FARC guerrillas and four soldiers were killed in a battle in the southwestern department of Caqueta.

The same day, 15 Colombian soldiers assigned to protect an oil pipeline were killed in a rebel ambush in the northeastern department of Arauca.

The FARC, which has an estimated 8,000 fighters, has been waging an insurgency against the government since its founding in 1964.

A second leftist guerrilla group, the National Liberation Army or ELN by its Spanish initials, also is active in the country and has so far not joined the peace talks taking place in Havana.