The Revolutionary Armed Forces of Colombia -- known as the FARC, for its acronym in Spanish -- holds an estimated 750 hostages in the jungles of South America, including three U.S. defense contractors. Many have been held for years.

Betancourt's plight has attracted worldwide attention.

She was abducted on February 23, 2002, after venturing into rebel territory while campaigning for the Colombian presidency. Videos later showed a slim Betancourt, sitting silently in a jungle setting.

News of her deteriorating health situation came after the FARC released six hostages this year when one of the freed hostages, Luis Eladio Perez, said that Betancourt had suffered from chronic liver problems since 2004.

He said he last saw her February 4 this year.

"Ingrid made a sign for me to go to the bathroom and she did the same and we were able to talk for about five minutes," Perez said. "I saw she was very ill and wasting away. She looked much worse than in that 'proof-of-life' video the rebels filmed in October."

Betancourt "seemed desperate" even though "she told me to stay calm and that the guerillas were giving her vitamins and calcium," he said.

French President Nicolas Sarkozy French made a personal plea to Betancourt's captors in April.

"Ingrid's health has deteriorated so much that her life is in danger. Ingrid is in danger of imminent death," Sarkozy said. "You have the power to save a woman from death and revive hope for all the other hostages still held."

FARC has justified hostage-taking as a legitimate military tactic in a long-running and complex civil war that also has involved right-wing paramilitaries, government forces and drug traffickers.

Colombia, the United States and European Union consider the FARC a terrorist organization.

As for the French-ordered humanitarian mission, some raised questions about its chances of success. They cited the fact that the humanitarian mission participants apparently have not had contact with the FARC.

"Who have they spoken to? Who is going to receive them?" he said. "What we know is that there is no communication with them."

A Colombian journalist, Carlos Lozano, also raised questions about the mission "because if one has not consulted with the FARC guerillas it would appear to me that this isn't going to work.