Colombia's main armed opposition group said at the weekend it would free two police officers and a soldier whose capture had threatened to derail peace talks.
The police officers were captured on January 25 while on an intelligence mission and the soldier was seized last week after a firefight that left four others dead.
The Revolutionary Armed Forces of Colombia (Farc) said it would release all three together, but did not set a date.
Farc agreed to stop using kidnappings as a source of funding before Cuba-based peace talks last year, but it made it clear on Tuesday that security forces were legitimate targets.
The rebels also declared a unilateral ceasefire for the start of the talks, which the government refused to join.
There has been a surge in violence since that expired on January 20, most recently three customs officers were killed in an ambush in northeastern state of Guajira on Friday.
And Farc launched a three-week "armed strike" in the poor, mostly rural northwestern state of Choco the same day, vowing to destroy any vehicles that take to roads.
Authorities said there was near full compliance with the strike over the weekend.
Soldiers killed six rebels, including a senior commander in a bombing raid on Thursday, Defence Minister Juan Carlos Pinzon said.
Mr Pinzon said brigade commander Jacobo Arango had been killed.
Mr Arango was close to Farc's chief negotiator Ivan Marquez, Mr Pinzon said.
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