France has said it is willing to take in members of the Colombian rebel group, Farc, who could be freed as part of a prisoner-hostage exchange.
Ms Rojas reportedly had a child after a relationship with a captor
The French Prime Minister, Francois Fillon, spoke hours after Farc said it was ready to release three hostages.
A communique stated they would include Clara Rojas, who was kidnapped with former presidential candidate Ingrid Betancourt in 2002, Prensa Latina said.
It said they would be handed to the President of Venezuela, Hugo Chavez.
Mr Fillon said the request to accommodate freed Farc rebels after a swap with hostages was made by Colombia's President, Alvaro Uribe.
"France has said it would be willing, along with other European and Latin American countries, to do that," he told RFI radio.
Mr Chavez's mediation, which was praised by Mr Fillon, was ended last month by the Colombian government.
Ms Rojas is a former aide to Ms Betancourt, who holds dual French-Colombian nationality.
Ms Rojas' son, who was born in captivity, and a former congresswoman, Consuelo Gonzalez, were the other two persons to be freed.
But the Colombian peace commissioner, Luis Carlos Restrepo, said Colombia remained cautious, given that the Farc had made similar announcements in the past.
'Nice Christmas gift'
In a statement sent to Prensa Latina, the Revolutionary Armed Forces of Colombia (Farc) said they had already given the order to release the three hostages to Mr Chavez or "whomever he opts to designate" - although it did not say when the handover would happen.
Clara Rojas's mother has called for her and Emmanuel's release
The Farc also reiterated their demand that President Uribe demilitarise a large area of south-western Colombia that would serve as a "meeting point" for a larger proposed exchange, of 45 hostages for 500 imprisoned guerrillas.
The rebel group described as "unacceptable" the government's current proposal for a smaller safe zone in what it called an "inhospitable, remote and clandestine" area, according to Prensa Latina.
In the Venezuelan capital, Caracas, Mr Chavez confirmed the Farc had also sent him the statement about the release.
"This appears to be a nice Christmas gift, especially for the families of these people," he said.
'Raised by guerrillas'
Ms Rojas, a 44-year-old lawyer and politician, was kidnapped in February 2002 along with Ms Betancourt, a French-Colombian national, during the latter's presidential campaign.
Last year, Colombian journalist Jorge Enrique Botero said in a book that Ms Rojas had given birth to a baby boy named Emmanuel following a relationship with one of her captors.
Ms Rojas's mother, Clara Gonzalez, broke down in tears when she heard news of the impending releases and said she hoped it was true.
"This is the moment I have waited for... this closes the circle," she told local radio.
Ms Betancourt's mother, Yolanda Pulecio, told the Venezuelan television channel, VTV, that she was "very happy for the families of Clara and Consuelo".
"The only thing I ask the guerrillas is that they also think of my daughter, who is suffering so much," she said.