A Colombian soldier kidnapped by rebels more than 10 years ago sent a "message of strength" to French-Colombian politician and fellow hostage Ingrid Betancourt in a video released on Sunday.

In the video, Pablo Moncayo, kidnapped by Marxist guerrillas in 1997, speaks to Betancourt, who was snatched during her 2002 presidential campaign.

"Don't give up. You have much to struggle and live for," Moncayo says in the video, which was received by his father, anti-kidnapping campaigner Gustavo Moncayo, and then released to the media.

"I send Ingrid a message of strength," the soldier says.

Colombia's rebels hold hundreds of hostages for ransom and political leverage, and they periodically provide such videos to prove that a hostage is alive.

Betancourt ran for president on an anti-corruption platform in a country where rebels, right-wing militias and common crime gangs fight for control of the cocaine trade.

Betancourt was last seen in a rebel video at the end of last year looking gaunt and despondent in a jungle camp. She is sick and has been chained up after repeated escape bids, say former hostages freed by the rebels.

France has renewed contact with guerrilla leaders to try and secure Betancourt's release after their main rebel contact was killed in a March Colombian military raid, French government sources said earlier this month.

Hostage negotiations with the four-decade-old Revolutionary Armed Forces of Colombia, or FARC, are stalled. The group has been weakened this year by the deaths of three top commanders and President Alvaro Uribe's U.S.-backed anti-rebel crackdown.