A French medical team on Thursday prepared to fly into Colombia's jungles to treat rebel hostage Ingrid Betancourt, a French-Colombian politician believed seriously ill after six years in guerrilla captivity.

A successful mission would be the first contact in years with Betancourt, the highest profile captive held by the Revolutionary Armed Forces of Colombia, but a tough FARC rebel statement gave no signal they would accept the initiative and made clear she would not be immediately freed.

President Alvaro Uribe says he will suspend military operations in the area once the team has the location where it will treat Betancourt, but it was unclear whether France had contacted rebels for the mission Paris believes is urgent.

"The French humanitarian mission has given us some information about where they think Ingrid Betancourt is being held," Uribe told the France 3 television channel. "We are ready to suspend military operations in the area in question."

French President Nicolas Sarkozy has demanded FARC commanders free Betancourt, but so far few details have been revealed about how the mission will treat her in a rebel camp.

In a hardline statement, FARC leader Rodrigo Granda said the killing of a senior commander in March complicated hostage negotiations and said rebels would not free Betancourt or any captives without a deal to exchange them for jailed rebels.

Granda did not refer directly to the mission for Betancourt or make clear if it would be allowed to visit captives.

A French aircraft transporting the mission was waiting at a Bogota military air base, fuelled and ready to fly to anywhere it was required inside Colombia, officials said.

Latin America's oldest left-wing insurgency, the FARC has been weakened by Uribe's U.S.-backed security crackdown, and violence from Colombia's four-decade conflict has ebbed as troops have pushed rebels into more remote areas.

FARC captives freed in recent months in deals brokered by Venezuelan President Hugo Chavez say Betancourt is very ill with hepatitis. Images from a rebel video released last year showed her gaunt in a hidden jungle camp and ex-hostages say she has been chained up after several escape attempts.

A rebel "proof of life" video released on Thursday by a left-wing senator involved in hostage talks showed the first images of captive lawmaker Oscar Tulio Lizcano in four years. It shows Lizcano asking Uribe to cede to rebel demands for a deal.

"I've been here imprisoned for more seven years now," Lizcano said in the grainy video showing him with four uniformed guerrillas. "Don't let us rot away in this jungle."

STALLED PEACE BID

France attempted a similar initiative in 2003 when it sent a military transport plane to Brazil's Amazon jungle region after Betancourt's family heard she might be released there.

But Brazil and Colombia were angered when the aircraft arrived without warning in the Amazon city of Manaus, close to the Colombian border, and the FARC was unaware of the mission.

Attempts to reach a deal to free 40 key hostages, including three U.S. contractors captured in 2003, in exchange for jailed rebels are deadlocked over a FARC demand that Uribe pull back troops from a swath of land to facilitate negotiations.

Two top FARC commanders were killed in March, including Raul Reyes, a key contact for attempts to negotiate a hostage accord. Those strikes have raised questions about the rebel leadership and the chances of reaching an agreement.

Colombia's attack on Reyes inside Ecuadorean territory also sparked an Andean crisis with Ecuador and ally Venezuela sending troops to their borders with Colombia.

Regional tensions are still high as Uribe, a staunch U.S. ally, accuses his leftist neighbours of sheltering the FARC.

Betancourt, a presidential candidate and her vice presidential proposal, Clara Rojas, were captured at a rebel roadblock while campaigning in 2002 in a southern province.

Rojas gave birth to a boy while in captivity. She was one of the hostages released in January under a deal arranged by Chavez, a left-winger who has stoked tensions with Bogota by calling for more political recognition for the guerrillas.

Started as a Marxist peasant army, the FARC once controlled large swaths of Colombia, but rebels have been driven back since Uribe came to office in 2002. U.S. and European officials label the FARC a cocaine-trafficking terrorist group.