A French group pressing for Colombian rebels to free thousands of hostages, some of whom have been held captive for more than a decade, warned on Saturday that armed intervention could lead to disaster for the captives. The International Federation of Committees for Ingrid Betancourt appealed to European leaders to ensure that the government in Bogata does not resort to force in an effort to free the captives. Concern has mounted that armed intervention could be the next step after President Alvaro Uribe on Friday withdrew his offer to negotiate a humanitarian prisoner exchange with the leftist Revolutionary Armed Forces of Colombia, or FARC, which holds thousands of hostages. The change of stance was triggered by a car bomb on Thursday reportedly set off by FARC that injured 23 people. "To return to the military option to liberate the hostages would be a drama without precedent," the federation said in a statement. "A military operation ... would be almost certainly fatal to the hostages." The group appealed to European Commissioner Jose Manuel Barroso, French President Jacques Chirac and other European governments to press Colombian authorities to ensure that a negotiated solution be found. There had been speculation that the Colombian government was trying to arrange a swap of hundreds of jailed rebels for some 60 people held by the FARC. However, on Friday Uribe ordered peace commissioner Luis Carlos Restrepo and other envoys to immediately cease contact with the guerrillas. He asked three European mediating countries — France, Spain and Switzerland — to provide military instead of diplomatic assistance to guarantee the release of the hostages, saying that a military solution was "the only option." French Foreign Minister Philippe Douste-Blazy, in a statement late Friday, reiterated France's opposition "to any effort to rescue the hostages by force." He said he was "convinced a peaceful solution is possible." Ingrid Betancourt, kidnapped in 2002 while campaigning for Colombia's presidency, also has French citizenship and has become a cause celebre in France. She is still being held by her captors.