Hostages held in Colombia by leftist guerrillas may still be alive after six years in jungle-captivity.

According to recent evidence, high-profile hostage Ingrid Betancourt and her fellow hostages are thought to still be living.

In a letter penned to her mother, former presidential candidate Betancourt described her day-to-day conditions as a “living hell”.

Ms Betancourt was kidnapped by the Revolutionary Armed Forces of Colombia in 2002 and has not been seen since.

Her letter also described how she sleeps under a mosquito net in a hammock, washes in rivers and how she has tried to escape.

The letter, along with other documents which include a grainy film of the captives, was seized from captured leftist guerrillas.

The documents show for the first time since 2003 that the hostages are alive but subjected to harsh living conditions and are being kept constantly on the move by the kidnappers known only as the FARC, to avoid detection by Government forces.

The letter was released a week after Bogota suspended efforts by Venezuelan President Hugo Chavez to negotiate a deal with the guerrilla group FARC to free its hostages.

Despite objections from Betancourt’s mother, the family released the letter in an attempt to put additional pressure on the Government to broker a deal with the FARC.

But the release of distressing images of the saddened and gaunt Ingrid Betancourt have caused great concern, leading the Government to relaunch attempts to exchange imprisoned left-wing FARC rebels for hostages kidnapped by the group.

Peace Commissioner Luis Carlos Restrepo said: “The President has made clear to the High Commissioner for Peace his immediate disposition to reach a humanitarian agreement to alleviate the suffering of those who remain in the hands of the FARC.”

As yet, however, there is no sign of an imminent agreement.