Suspected FARC rebels killed 13 soldiers and wounded one in an attack staged in Colombia's Arauca province, an army spokesman told Efe.
Two non-commissioned officers and 11 enlisted men died in the attack, which occurred outside the city of Tame on Saturday.
The wounded soldier was transported to a hospital in the area.
Army commander Gen. Juan Pablo Rodriguez went to the area to oversee the operation to track down the Revolutionary Armed Forces of Colombia, or FARC, guerrillas who carried out the attack.
The dead soldiers belonged to the 18th Brigade, initial reports said.
Both the FARC and the smaller National Liberation Army, or ELN, guerrilla groups operate in Arauca.
Officials, meanwhile, said the government delegation participating in peace talks with the FARC plans to return to Havana to continue the negotiations.
President Juan Manuel Santos on Friday ordered the negotiators to return to Bogota to review the state of the talks after the FARC announced it would take "a pause" in the negotiations.
The FARC, Colombia's oldest and largest leftist guerrilla group, was founded in 1964 and operates across a large swath of this Andean nation.
The Colombian government has made fighting the FARC a top priority and has obtained billions in U.S. aid for counterinsurgency operations.
The FARC is on both the U.S. and EU lists of terrorist groups. Drug trafficking, extortion and kidnapping-for-ransom are the FARC's main means of financing its operations. EFE