The Colombian government has banned a leading paramilitary leader from peace talks after he was blamed for abducting a former senator and eight others.
The kidnap of Gnecco in the run-up to peace talks has incensed the government
Jose Gnecco remains missing after being kidnapped on Monday, though his family and chauffeur have now been freed.
The government said "strong signs" pointed to the involvement of right- wing AUC paramilitaries in the kidnap.
It stripped Rodrigo Tovar Pupo - alias Jorge 40 (George 40) - of immunity from arrest during forthcoming peace talks.
The announcement has further undermined a peace process that few believe will succeed, says the BBC's Jeremy McDermott in Bogota.
Mr Gnecco was kidnapped along with his wife, five children, niece and chauffeur, as they drove between the cities of Santa Marta and Riohacha on Monday.
All except Mr Gnecco were picked up in the foothills of the nearby Sierra Nevada mountains in the early hours of Tuesday morning local time. Reports say their release followed an army operation.
A local army general, Mario Montoya, was quoted as saying that Mr Gnecco's wife, Laura Giraldo, and one of their children had received bullet wounds.
Gen Montoya said a cash reward had been offered for information leading to the return of Mr Gnecco and the capture of his kidnappers.
Earlier, in a statement, the office of President Alvaro Uribe said there "strong signs... [of] at least the participation" of paramilitaries from the United Self-Defence Forces of Colombia (AUC) in the kidnap.
It said an arrest warrant had been issued for the arrest of Mr Tovar and fellow commander Hernan Giraldo Serna - whom Gen Montoya also named as responsible for the abduction.
Arrest warrants against the leaders were suspended on 15 June provided they remain within a 368 sq km (142 sq mile) safe haven set up in the municipality of Tierralta, Cordoba province.
"The government supports and believes in peace
processes that are serious, not deceptive," said the government in its statement.
"Peace processes and safe zones can
not become temporary shelters used to continue committing criminal acts, nor places of impunity."
The peace talks, due to begin on Thursday, aim to demobilise the group's 13,000 or so fighters by 2006.
In return, the group wants guarantees of safe conduct and protection against extradition to the US on drug trafficking charges.
Of the 10 paramilitary negotiators, five have outstanding US extradition warrants for narcotics and another three, including Mr Tovar, are under investigation.
The AUC - set up 22 years ago to fight left-wing rebels - is accused of some of the worst human rights atrocities in Colombia over the past decade.
About 3,500 people are killed each year in Colombia's civil war, now four decades old.