A letter from Ingrid Betancourt, the French-Colombian politician held by Colombian rebels, has been released, detailing her life in captivity.
Ms Betancourt says she is physically weakened by her captivity
In the letter, addressed to her mother, Ms Betancourt says her strength has diminished, her appetite has gone, and her hair is falling out.
"Here, we are living like the dead," she writes.
Ms Betancourt, a former presidential candidate, was captured in 2002 by Marxist Farc rebels.
The letter was seized during the arrest of three suspected Farc members in Bogota.
Its publication follows the release of video footage of the hostages, also found during the capture of the Farc rebels.
"Physically I am in bad shape," Ms Betancourt writes in the letter.
"I don't eat anymore, my appetite is blocked, my hair falls out in clumps... I don't have enthusiasm for anything because the only answer for everything here in the jungle is 'No'."
She reveals that she has been able to hear messages from her family and other supporters on a Colombian radio station and asks her son and daughter to send her three messages every week, even though she is not able to respond.
"I don't need anything else, but I need to be in contact with them," she says.
And she describes how her captors have confiscated most of her belongings, leaving her without any mental stimulation.
"For three years, I have been asking for an encyclopaedia to read something, to learn something, to keep alive my intellectual curiosity," she writes.
Farc, which has been fighting the Colombian government for many years, is demanding the creation of a demilitarised zone in the country in return for the release of Ms Betancourt and over 40 other hostages.
A recent attempt by Venezuelan President Hugo Chavez to negotiate with the rebels for the hostages' release ended in controversy, when Colombian President Alvaro Uribe ended Mr Chavez's role, accusing him of breaking protocol by being in direct contact with Colombia's army chief.
Because Ms Betancourt holds French citizenship, French President Nicolas Sarkozy has also been directly involved in attempts to free her and her fellow hostages.
In response to Ms Betancourt's letter, President Sarkozy expressed concern about "the obvious precariousness" of her health and "about her despair".
In her letter, Ms Betancourt referred to her French background, saying: "My heart belongs also to France... When the night is at its darkest, France is a lighthouse."