Final preparations are under way in Colombia for the promised release of the last 10 military and police captives held by the Farc rebel group.
Two Brazilian helicopters are standing by to collect the first hostages from a secret jungle location on Monday.
Military operations in the area have been suspended.
President Juan Manuel Santos has made the release of all hostages one condition for opening talks with the Farc to end five decades of conflict.
He also wants the left-wing group to end all attacks and stop drug trafficking and the recruitment of children.
The hostage release is being co-ordinated by the International Committee of the Red Cross (ICRC) and a group of Colombian mediators led by the former senator Piedad Cordoba.
Ms Cordoba has said the releases are a unilateral "gesture of peace" by the Farc that should lead to dialogue.
Relatives of the hostages have gathered in the city of Villavicencio in central Colombia, from where the Brazilian helicopters are due to set off.
The Farc have said they will release the captives - which they call "prisoners of war" - in two groups on 2 and 4 April.
All have been held for well over a decade after being captured in guerrilla attacks.
For many years the rebels tried to use captured members of the security forces as bargaining tools to try to secure the release of jailed guerrillas.
But in February the Farc announced that it would free the last 10 hostages and promised to end the practice of kidnap for ransom.
The Revolutionary Armed Forces of Colombia (Farc) have been fighting for power in Colombia since the 1960s.
But over the past decade they have suffered a series of setbacks, losing several top commanders and much of their strength.
After drug trafficking, kidnapping for ransom has been the group's main source of income, but the practice has drawn national and international condemnation.