|Tuesday's march against FARC was organised by civic groups with the support of the Colombian government [Reuters]
Colombia's largest armed rebel group has pledged to free six of 11 captive members of the country's security forces, hours after thousands marched nationwide to demand the freedom of all hostages.
"We'll continue exploring with you all the ways that may lead to this noble undertaking and to carry out... the release
of the war prisoners," the Revolutionary Armed Forces of Colombia (FARC) said in a statement on Tuesday without giving details of timing or names.
"It generates tremendous concern, real anguish, for them [FARC] to see Colombians pressuring them and rejecting their terrorist methods."
- Oscar Naranjo, chief of police
FARC currently holds 11 police and soldiers with the goal of trading them for the several hundred imprisoned guerrillas. It is also believed to be holding up to 300 civilians for ransom.
Colombian President Juan Manuel Santos responded that he would not trade hostages for imprisoned guerrillas, but indicated that he was open to a future dialogue if the Marxist group demonstrated "true political will".
"What we want to see is a real will to reach a peace agreement, and one of the ways to express that will is freeing the hostages unilaterally, without conditions and without a show," Santos said.
"Free them and then we can sit down to see if there are possibilities of a dialogue but to talk about a humanitarian agreement, not a prisoner exchange," he said.
Earlier on Tuesday, protesters marched in Bogota, Cali, Medellin and other cities, chanting, "Freedom! Freedom! Freedom!"
The demonstrations were organised by civic groups with the support of the government, which gave public employees time off to participate and openly called on Colombians to join the protests.
General Oscar Naranjo, Colombia's chief of police, said the protests were a major concern for FARC, Latin America's oldest guerrilla group which remains entrenched in large areas of the country with an estimated 8,000 fighters despite the losses of key leaders in recent years.
"It generates tremendous concern, real anguish, for them to see Colombians pressuring them and rejecting their terrorist methods," he said.
Many of Tuesday's protesters also called on the military not to put hostages' lives in danger with risky rescue attempts.
FARC's longest held hostage: Luis Alfonso Beltran
The marches were held 10 days after the assassination of four captives - three policemen and a soldier - who had been held hostage for more than 12 years. Among them was FARC's longest-held hostage, Jose Libio Martinez, who was kidnapped in 1997.
The four were shot by their guards when their jungle camp came under attack, authorities said. FARC blamed the deaths on a "senseless" military rescue attempt and said it had previously pledged to release the prisoners.
"We profoundly deplore that four of the six prisoners of war that we were going to free unilaterally in response to their petition in August, have died in an irrational military rescue attempt by the Colombian army, when they were marching to the place where we planned to turn them over to you," it said.
"We are surprised by the attitude of the Colombian government, which we do not doubt was aware of what we had determined to do. The FARC wanted to free them alive, but the government of Juan Manuel Santos preferred to return them dead to their loved ones."