Leaders of Colombia's main rebel group on Tuesday rejected a French medical mission that flew to Bogota to aid ailing hostage Ingrid Betancourt, a presidential candidate who was kidnapped six years ago.

The group said France had not coordinated with the rebels before the French plane arrived.

"We don't respond to blackmail or media campaigns," the rebels said.

The communique from the ruling secretariat of the Revolutionary Armed Forces of Colombia was dated April 4, the day after a French government plane arrived in Bogota, carrying doctors and diplomats who hoped at least to see Betancourt, a French-Colombian citizen.

The statement noted that the group, known as the FARC, had released six hostages earlier this year as a "gesture of generosity and political will" and called again on the Colombian government to grant a demilitarized zone where imprisoned rebels could be swapped for guerrilla-held hostages.

"Rebels imprisoned in the jails of Colombia and the United States are our priority," the rebels said in a statement posted Tuesday on a Web Site sympathetic to the FARC.

Concerns for Betancourt's welfare are running high after hostages who spent time with her and were later released said that she was depressed and suffering from Hepatitis B.

A document the Colombian government says was recovered from a dead rebel commander's laptop computer describes Betancourt as having a "volcanic temper" and said she "is rude and provokes the guerrillas who are in charge of keeping her."

The document, one of many being studied by Interpol to ascertain their authenticity, is dated Feb. 28, 2008, and was apparently written by Raul Reyes, the FARC spokesman who killed at the beginning of March in a military strike.

Betancourt is one of dozens of hostages being held by the rebels, who want to swap them for hundreds of rebels jailed in Colombia and two rebels imprisoned in the United States. The rebels' captives include three U.S. defense contractors whose plane was shot down during a drug surveillance mission.

The office of French President Nicolas Sarkozy, who sent the mission to Colombia, said in Paris that it did not immediately have any comment on the FARC's statement.