Colombia on Friday released videos seized from rebels that for the first time in years show Colombian-French politician Ingrid Betancourt, three US nationals and other prominent hostages held by leftist insurgents.

The government said the footage, evidently taken to prove the hostages are still alive, appears to have been taped in October.

Colombian President Alvaro Uribe claimed there were indications the insurgents tortured Betancourt, a former senator who was captured by the Revolutionary Armed Forces of Colombia (FARC) while running for the presidency in 2002.

"The video indicates torture, particularly in the case of Dr Ingrid Betancourt and Senator Eladio Perez," Uribe said.

But Betancourt's sister Ingrid insisted in Paris there was nothing to suggest the former senator had been tortured. She claimed Uribe's statements endangered efforts to have the hostages released.

The mother of one of the US hostages expressed renewed hope after the videos were released.

"I think that maybe with this proof of life there will be some increased international efforts to go ahead with the humanitarian exchange," Lynne Stansell told AFP.

The five videos, provided the first images in years of Betancourt and 15 other hostages, including US Defense Department contractors Marc Gonsalves, Keith Stansell and Thomas Howes.

The three Americans appeared in better health than Betancourt, who was chained and looked depressed. The Americans were kidnapped in February 2003 after rebels shut down their plane during an anti-drug surveillance mission.

Lynne Stansell said her son "looks as good, or maybe even better than you would anticipate after five years almost." But she added that her son lost a lot of weight.

Four of the videos bear October dates, but the one showing the Americans is dated January 1, which government officials say appears to have been an error as one of the 11 hostages shown on that tape says: "Today is October 23."

Authorities said the tapes included messages to the hostages' families, but only released footage without sound.

The Colombian military also seized pictures of the hostages and letters written by them.

One letter dated October 24 was written by Betancourt to her mother, Yolanda Pulecio, authorities said. In a letter dated November 26, 2006, Howes makes changes to his will.

"We are extremely moved, very very moved to see these images of my sister," Astrid Betancourt said on French television.

"So far we have only seen a single photograph. She is sitting at a little table. She seems quite thin with very long hair. She's looking down, sad. It looks like her hand is chained.

French President Nicolas Sarkozy, who has taken a close interest in the case, was "happy above all for the family," his spokesman said.

The Americans and Betancourt are among about 45 hostages the rebels want to swap for 500 FARC prisoners. Uribe has rejected guerrilla demands that he create a demilitarized zone for negotiations.

Prospects for an exchange dimmed last week after Uribe ended mediation efforts by Hugo Chavez, accusing the Venezuelan president of siding with the FARC.

Colombian Senator Piedad Cordoba, who had worked alongside Chavez as a mediator, said the footage and the letters were meant to be given to the Venezuelan president, who said earlier the insurgents had promised to supply proof the hostages are alive.