Dozens of guerrillas from the Mariscal Sucre unit of the Revolutionary Armed Forces of Colombia, or FARC, guerrilla group died in the military bombardment of a camp in Nariño province, army spokesman Col. Luis Emilio Cardoso said.
At least 20 rebels died in the raid, media reports said.
Cardoso, however, said the Attorney General's Office was in charge of removing the bodies and had not yet released a body count.
The bombardment occurred on Saturday night outside Ricaurte, a city in southwestern Colombia near the border with Ecuador, Cardoso said.
The death toll from the bombardment is at least 20, army Brig. Gen. Jorge Alberto Segura told Caracol Radio.
Last week, the first round of talks in Havana between the Colombian government and the FARC ended with progress on mechanisms for incorporating civil society into the negotiating process, which is aimed at bringing an end to a decades-long armed conflict.
Negotiators representing President Juan Manuel Santos's administration and the guerrillas will resume talks on Wednesday after the two sides agreed to organize a citizens' forum on agrarian policy and to launch a Web site for receiving proposals from the general public.
The accord establishing a framework for the peace process was signed on Aug. 26 in Havana after six months of secret exploratory discussions on the communist-ruled island under the auspices of the Cuban and Norwegian governments.
The initial phase of the talks began on Nov. 19.
The most recent peace process with the rebels, during the 1998-2002 government of President Andres Pastrana, took place in a demilitarized area of southern Colombia - dubbed "Farclandia" - and collapsed amid mutual recriminations.
The FARC has battled a succession of Colombian governments since 1964. The insurgency swelled to nearly 20,000 fighters in the early 2000s, but now numbers around 8,500 combatants.
Colombia's armed forces, bolstered by billions of dollars of aid from the United States, have scored dramatic successes against the FARC in recent years, but the rebels remain capable of inflicting significant damage on the military and on vulnerable infrastructure. EFE