Demonstrations are taking place across Colombia Friday to urge leftist FARC rebels to free hundreds of hostages. But the FARC says it will not release any of the captives until a deal is struck to free guerrillas held in Colombian prisons.

Thursday's FARC statement came hours after a French-led medical mission arrived in Colombia in an effort to provide treatment to French-Colombian rebel hostage Ingrid Betancourt. She has been held captive for more than six years and is believed to be gravely ill. The medical mission, however, remains stalled as officials wait for the FARC to grant them access.

French Foreign Minister Bernard Kouchner told Associated Press television that President Nicolas Sarkozy is ready to travel to Colombia with Venezuelan President Hugo Chavez to help win Betancourt's release.

President Sarkozy has made her release a foreign policy priority for his government.

Betancourt was kidnapped in 2002 while campaigning for the Colombian presidency. She is one of at least 700 hostages being held by the FARC in secret jungle camps. Three Americans are among them.