Residents and policemen carry the corpses of five soldiers killed by the Revolutionary Armed Forces of Colombia (FARC) guerrilla during combat in a rural area of Santander de Quilichao, Department of Cauca, Colombia, on December 19, 2014
Bogota (AFP) - Leftist rebels in Colombia began a unilateral ceasefire Saturday hailed as a key step in peace negotiations -- but uncertainty marred the truce, which the guerrillas threatened to break if attacked by the army.
"Today, the FARC's unilateral and indefinite ceasefire began. I hope it will turn into a bilateral and final ceasefire, and we can put an end to a war that's lasted more than 50 years," President Juan Manuel Santos said at a ceremony in La Guajira in the country's northeast.
Santos, who earlier had called the ceasefire "a positive gesture that goes in the right direction," added that he hoped the move would facilitate ongoing peace talks in Havana.
In a message published shortly before the ceasefire took effect just after midnight, the FARC welcomed Santos' stance on the truce, and asked him "not to stand in the way of the people's desire to know their country without the roar of bombs and machine guns."
Under the ceasefire, the Revolutionary Armed Forces of Colombia (FARC) says its fighters will only engage in hostilities if they come under attack first.
The FARC had declared Christmas ceasefires in each of the past two years, but this is the first without an expiration date.
Santos, who has made the peace talks his top political priority, has rejected any bilateral ceasefire, saying the guerrillas could take advantage of a truce to regroup, dragging out the conflict.
On the eve of the ceasefire Friday, FARC fighters ambushed a patrol in western Colombia, killing five soldiers.
The attack had a familiar ring for Colombians.
The rebels had also staged attacks just before their 2012 and 2013 ceasefires, showing their strength before putting down their guns.
But officials said the attack didn't threaten the peace talks aiming to end Latin America's longest-running conflict, which over the past 50 years has killed some 220,000 people and displaced 5.3 million more.
The talks only just re-started after being suspended when the FARC captured an army general who headed an anti-rebel task force in the jungle-covered region of Choco, their highest-ranking captive ever.
The FARC released the general on November 30 in order to revive the stalled talks.
Though the ceasefire is an important step, it will not necessarily see the end of armed conflict in Colombia.
Another rebel group called the National Liberation Army (ELN) may try to take advantage of the lull in hostilities.
The second-largest guerrilla group after the FARC, the ELN this week kidnapped a mayor in Choco and killed three policemen in a separate attack.