Colombia has offered to suspend the sentences of jailed FARC members if the rebels free their hostages, including former presidential candidate Ingrid Betancourt.
Colombia Peace Commissioner Luis Carlos Restrepo says if some captives are liberated immediately, the process of exchanging rebels for dozens of hostages could begin.
The move comes amid reports that Betancourt is ill with hepatitis B and malnutrition and is in a very delicate state of health.
Colombia's ombudsman Volmar Perez said his office has received reports that Betancourt has become so ill that her rebel captors sought medical attention for her last month in southeastern Colombia. Perez also says his office has been told that Betancourt is suffering from leishmaniasis, a parasitic skin disease caused by insect bites. Betancourt has been held by FARC rebels for six years.
Both the French and Venezuelan governments have become involved in efforts to win her release.
The FARC is holding at least 700 people in secret jungle camps for ransom or political leverage. Three Americans are among the hostages.
The United States, European Union and Colombian government have designated the FARC as a terrorist organization.
Some information for this report was provided by AFP and AP.