The Colombian government has begun the process of freeing imprisoned rebels in a move President Alvaro Uribe says is a unilateral goodwill gesture.
The releases began early on Tuesday morning
The first 56 of some 200 rebels were moved from jail to attend a four-week rehabilitation course prior to release.
President Alvaro Uribe on Monday freed a guerrilla leader at France's request.
Officials hope developments will bring about the release of 56 hostages, including a French-Colombian woman, but the rebels have ruled out a response.
With a heavy police escort, three buses took a group of 56 prisoners belonging to the Revolutionary Armed Forces of Colombia (Farc) from a jail north of the capital, Bogota, early on Tuesday.
From a military airfield they were to be flown to the central province of Tolima to attend a government-sponsored rehabilitation course.
The rebels are the first of nearly 200 the government plans to release.
In a separate gesture on Monday, Rodrigo Granda, known as the Farc rebel group's "foreign minister", was freed.
Mr Uribe announced the rebel leader's release in a TV and radio address.
"The government has guaranteed his safe passage so that he may promote peace," Mr Uribe said.
The Colombian president said that Mr Granda was released at the request of the French President Nicolas Sarkozy.
Ingrid Betancourt's fate has been closely followed in France
In a statement on Tuesday, Mr Sarkozy welcomed Mr Uribe's "very important and courageous decision" and expressed the hope that the Farc would respond.
The French authorities have been pushing for the release of Ingrid Betancourt, a former Colombian presidential candidate, who has French citizenship. She was kidnapped more than five years ago.
Mr Sarkozy met Ms Betancourt's family in Paris on Tuesday, telling them he would raise her situation with world leaders meeting at the G8 summit in Germany this week.
Mr Uribe is hoping that Farc will reciprocate his gesture by releasing the hostages they hold.
But in a communique over the weekend, the group called the government move a farce.
It said it would discuss the possibilities of a prisoner exchange if and when the government granted a safe haven as a venue for talks - a request repeatedly rejected by Mr Uribe.
"I cannot accept a demilitarised zone but I also cannot stop seeking the release of my compatriots and the three kidnapped Americans," Mr Uribe said, referring to US citizens kidnapped in 2003.