A leader of Colombia's largest rebel group said in an interview published in a French newspaper Tuesday that a former presidential candidate who has been held hostage for more than four years is doing well.

Ingrid Betancourt's supporters demanded proof that she is still alive. Betancourt, who holds dual Colombian-French citizenship, was kidnapped while campaigning for the Colombian presidency in 2002.

Raul Reyes of the Revolutionary Armed Forces of Colombia, or FARC, said in an interview with France's L'Humanite newspaper that Betancourt "is doing well, within the environment she finds herself in. It's not easy when one is deprived of freedom."

He said FARC is "willing" to hand over Betancourt, three American defense contractors and several Colombian police officers and politicians abducted over the past six years.

The rebels' recent claims of willingness to release hostages are a reversal.

The Colombian government, backed by Spain, France and Switzerland, has been trying to orchestrate the release of 60 hostages held by the FARC in exchange for scores of jailed rebels.

But the FARC rejected the government offer, saying earlier this year that it would never strike a deal with President Alvaro Uribe. Observers say Uribe's overwhelming victory in elections last month may have forced the guerrillas to reconsider their position.

Herve Marro, who leads a French group demanding Betancourt's release, expressed skepticism about Reyes' claim.

"We have been disappointed so many times. If he says she is doing well, then give us proof," he said. "Then we will have reason to believe it." The family has not seen evidence that Betancourt is alive since 2003.

The Colombian Embassy in Paris would not comment on the claim.