Hundreds of thousands of Colombians have staged nationwide protests calling for an end to kidnapping and the civil conflict which has lasted 44 years.
The protesters demanded the release of the Farc's hostages
The centre of the capital Bogota was shut as protesters marched, demanding the release of some 3,000 people still being held hostage by different groups.
The rallies were seen as a rare show of national unity.
The calls for peace were prompted by the killing in June of 11 politicians held by the left-wing Farc movement.
The Farc, or Revolutionary Armed Forces of Colombia, said the hostages died when unidentified gunmen attacked the jungle prison camp where they were being held.
Said to be 3,000 in total
Held by rebels, paramilitary groups and criminals
Include some 60 political hostages held by Farc
The politicians were among a group of some 60 hostages - including Colombia's former presidential candidate Ingrid Betancourt and three US defence contractors - who the Farc want to swap for hundreds of their imprisoned comrades.
President Alvaro Uribe accused the rebels of killing the men in cold blood, saying there had been no military operations in the western Valle del Cauca region at the time.
'Freedom without conditions'
The demonstrators took to the streets in major cities and small towns throughout Colombia, demanding "freedom without conditions now" for the people being held hostage by guerrillas, right-wing paramilitary groups and criminal gangs.
Former Colombian President Cesar Gaviria said the march in Bogota was a "notification to those violent people to prove that this society is united in the fight against kidnapping".
"We hope everyone in the international community supports this cause in order to eliminate this scourge over Colombian society," he said.
Appearing in front of the crowds in the centre of the capital, President Uribe greeted the families of those killed by the guerrillas and the relatives of those still held hostage.
The BBC's Jeremy McDermott says the government is seeking to channel the national outrage at the killing of the politicians into support for Mr Uribe's hardline stance against the rebels.
The nationwide protests have revealed the depth of feeling against the rebel killings and the guerrilla war to overthrow the state, but it is unlikely that the Farc will pay any heed, our correspondent says.