President Alvaro Uribe on Friday withdrew his offer to negotiate a humanitarian prisoner exchange with leftist rebels after blaming the Revolutionary Armed Forces of Colombia for a car bomb that injured 23 people. In an emotional speech at the military university in Bogota where the blast took place, Uribe said intercepted phone calls established that Thursday's attack was planned by the top leader of the group known as the FARC, Jorge Briceno, whose nom de guerre is El Mono Jojoy. A series of conciliatory remarks by Uribe in recent weeks had fed speculation the government was trying to arrange a swap of hundreds of jailed rebels for some 60 political prisoners held by the FARC, including three American defense contractors. But Uribe on Friday squashed hopes for an eventual deal, ordering peace commissioner Luis Carlos Restrepo and other envoys to immediately cease contact with the guerrillas. He also asked three European peace facilitators — France, Spain and Switzerland — to provide military instead of diplomatic assistance to guarantee the release of the hostages, some of whom have been captive for more than a decade. "The only option left is a military rescue," said Uribe. Uribe's hardened stance drew swift condemnation from hostage family members. "The president's speech condemns to death the kidnapped hostages," said a weeping Yolando Pulecio, mother of Ingrid Betancourt, a French passport holder who was kidnapped in 2002 while campaigning in the jungle for Colombia's presidency.