At least seven Colombian soldiers were killed and five others were wounded in fighting with rebels who tried to seize a town on Wednesday, the military said.
The gunbattle erupted when rebels tried to take over Milan in the southern state of Caqueta and were repelled by dozens of troops, army Gen. Emiro Barrios said.
It was the deadliest clash between Colombian troops and rebels of the Revolutionary Armed Forces of Colombia so far this year. On Jan. 29, four soldiers were killed in fighting with rebels elsewhere in the country.
The violence came while the Colombian government and FARC rebels are pursuing peace talks in Cuba.
Barrios said a group of rebels estimated at about 150 fighters had clashed with three platoons, or about 90 troops.
He said that in addition to the seven soldiers killed, five were wounded and were taken out of the area to be treated. No soldiers were missing, he said.
The combat occurred in a rural area considered a traditional stronghold for the leftist guerrillas.
The FARC declared a two-month unilateral cease-fire when the formal peace talks in Havana began, but that cease-fire lapsed on Jan. 20. The FARC had urged the government to join the cease-fire, but President Juan Manuel Santos has refused.
Santos argues that agreeing to a cease-fire would give the FARC the opportunity to regroup, as it did during failed 1999-2002 talks when it was granted a Switzerland-sized safe haven.