The son of Ingrid Betancourt, the Franco-Colombian senator who was captured by rebels while campaigning for the presidency in 2002, told reporters that his mother needed a blood transfusion within hours to stay alive.

At a news conference in Paris, Lorenzo Delloye said his mother suffered from hepatitis B and a skin disease, which immediately need to be treated.

On Tuesday, French president Nicolas Sarkozy appealed to the leaders of Colombia’s largest rebel group, calling for the release of their French hostage Ingrid Betancourt, as her health was threatened.

"The latest information reaching us regarding Ingrid Betancourt is profoundly worrying. It confirms that Ingrid's state of health has deteriorated so seriously that her life is threatened," Sarkozy said.

"Ingrid is in danger of imminent death. She no longer has the strength to resist an interminable captivity which is turning into tragedy," he added.

Sarkozy told Manuel Marulanda, leader of the Revolutionary Armed Forces of Colombia (FARC), the group which captured Betancourt six years ago, that he had the occasion to remain an important character in history, through the humanitarian gesture of releasing the sick hostage.

France hopes to send a doctor in Colombia soon enough to save Betancourt, who reportedly began a hunger strike on February 23, the sixth anniversary of her captivity.

According to CNN, Sarkozy asked Colombian president Alvaro Uribe to help France by guaranteeing safe passage of the humanitarian mission, which will also include Red Cross members. The Colombian president agreed to help, and said he would suspend all military operations in the area.

FARC is reportedly holding around 750 hostages in Colombia’s jungles and has released six of them in the last three months.