Sarkozy's office said Bernard Kouchner, the foreign minister, would travel to Colombia to discuss the situation with regional governments.
 
Protesters in France and Colombia have been
calling for Betancourt's release [AFP]
A French government aircraft had been waiting at a Bogota airstrip for days with doctors hoping to reach Betancourt
 
The Farc said earlier on Tuesday that they had refused to allow the mission as France had not co-ordinated with them on it.
 
"We don't respond to blackmail nor media campaigns," the rebels said in a statement issued through the Bolivarian news agency.
 
The French mission was "the result of the bad faith of Uribe [the Colombian president] before the [French] government and heartlessly mocks the expectation of the relatives of the prisoners", the group said.
 
Deal offered
 
The Farc (Revolutionary Armed Forces of Colombia) snatched Betancourt in February 2002 as she campaigned for the Colombian presidency.
 
She is the most high-profile of around 40 "political" hostages the group is holding in hopes of a swap for 500 of its own members in Colombian and US jails.
 
The Farc has carried out a 40-year
war against the government [GALLO/GETTY]
The Colombian government has offered an amnesty to the rebels as part of a deal to release the hostages, although the Farc has yet to respond to the offer.
 
The statement said the rebels had released six hostages earlier this year as a "gesture of generosity and political will" and called again on the Colombian government to set up a demilitarised zone where imprisoned rebels could be swapped for hostages.
 
The four-point statement, dated Tuesday, added that the Farc leadership "deeply" lamented that while they were working "in the direction of a prisoner swap", Uribe was "planning and executing the assassination of commander Raul Reyes".
 
Colombian forces killed Reyes in an attack on a rebel camp in Ecuador on March 1 that sparked a regional diplomatic crisis.
 
The Farc is holding hundreds of other Colombian hostages as part of what it has said is a Marxist armed struggle against the Colombian government.