The men were transferred from a low-security prison last week
Colombia's right-wing paramilitary leaders have pulled out of a peace process with the government over their transfer to a high-security prison.
A spokesman for the paramilitaries said the pull-out reflected a lack of confidence in the government.
On Friday, the 59 leaders were moved to a tougher facility over concerns that they were planning illegal activities.
The paramilitaries - established 20 years ago to combat left-wing rebels - signed up to the peace deal in 2004.
The pull-out came after more than three hours of talks between paramilitary leaders and government peace negotiator Luis Carlos Restrepo.
"This is simply a matter of ending a process where there is no confidence, (a process) filled with tricks, no honour of agreements and where there is no commitment," Ernesto Baez, a spokesman for the paramilitaries, told television station CMI.
However, correspondents say it remains unclear what impact the leaders' declaration will have, given that they have already turned themselves in to the authorities.
The paramilitaries agreed to a peace deal in 2004
The United Self-Defence Forces of Colombia (AUC) - an umbrella group for right-wing paramilitaries - were created by landowners and drug-traffickers to combat left-wing rebels.
They are accused of drug-trafficking, extortion and killing civilians.
Since the peace process began in 2004, more than 30,000 fighters have disarmed. Leaders face a maximum of eight years in prison under the terms of the deal.
But President Alvaro Uribe has accused them of ordering assassinations from their cells ,and there were also rumours that a jail break was being planned, the Associated Press news agency reported.
The move comes amid an ongoing scandal linking Colombian lawmakers to the group.
Prosecutors have named six politicians - members of Mr Uribe's governing coalition - that they want to question over the alleged links.