FACTBOX: Colombia's rebel-held hostages

(Reuters) - A French medical mission has arrived in Colombia in an attempt to treat rebel hostage Ingrid Betancourt, a French-Colombian citizen believed to be seriously ill after more than six years in guerrilla captivity.

The following are some facts about hostages held by the Revolutionary Armed Forces of Colombia, or FARC, Latin America's largest and oldest left-wing rebel group.

* Betancourt, a French-Colombian politician, was running for president when she was captured while campaigning in 2002 in a southern province. Her vice presidential candidate Clara Rojas was also kidnapped at the same time. Rojas later gave birth to a boy, Emmanuel, while in captivity in a secret jungle camp.

* Rojas and Consuelo Gonzalez, a lawmaker, were freed in January after six years in captivity. Venezuelan President Hugo Chavez brokered their release, but his calls for the FARC to be removed from lists of terrorist organizations fueled diplomatic tensions with Colombia.

* Three U.S. Defense Department contract workers -- Thomas Howes, Marc Gonsalves and Keith Stansell -- were kidnapped when their aircraft crashed while on an anti-narcotics mission in February 2003. Rebels say the men must be exchanged for two FARC members held in U.S. prisons.

* In late 2007, the army arrested a group of guerrillas carrying "proof of life" documents including a video that showed a gaunt Betancourt sitting in the jungle and the three Americans. In a letter to her mother, Betancourt said she was barely eating and that her hair was falling out.

Hostages released by the guerrillas say Betancourt is now seriously ill. She is believed to be suffering from hepatitis

B.

* Betancourt and the three Americans are among 4O key hostages the FARC wants exchanged for jailed rebels. Some hostages have been held for a decade. The government says the FARC has kidnapped another 700 people for ransom, but it is unclear how many are still being held.

* The FARC wants Uribe to pull troops back from a New York City-sized rural area for a safe haven to negotiate a hostage swap. Uribe, whose father was killed in a botched FARC kidnapping, says that would allow the rebels to regroup, but he has offered a smaller zone under international observation.

* French President Nicolas Sarkozy last year persuaded Uribe to release a top jailed rebel in an effort to break the deadlock. France, Switzerland and Spain are now engaged in efforts to secure a possible hostage deal.

* Uribe has offered to free jailed rebels and allow some to leave for France in an attempt to prompt FARC commanders to free hostages. But the FARC has yet to respond to his offer.

* Two top FARC commanders were killed in March, including Raul Reyes, a key contact for attempts to negotiate a hostage accord. The strikes against the FARC have raised questions about who now speaks for the rebel leadership.

(Reporting by Patrick Markey in Bogota; Editing by Kieran Murray)