US officials had ruled out releasing Simon Trinidad, who is serving a 60-year prison term for the kidnapping of three Americans held hostage in Colombia for more than five years.

But Jesus Santrich, a member of the FARC negotiating team, said the group, which first made the request on Friday, was still hoping that US President Barack Obama would pardon Trinidad.

"We don't want to lose faith, hope, that President Barack Obama will send Colombia a message of peace with a favorable outcome for this request," he told reporters.

"We are confident that Simon will arrive at the negotiating table." However, the State Department indicated Tuesday that the US position against Trinidad's release had not altered.

"To my knowledge, it has not changed," spokeswoman Victoria Nuland said in Washington.

Negotiators representing the FARC and the Colombian government formally launched their first peace talks in a decade at a session in Oslo, Norway, and then moved to Havana for in-depth negotiations, which began November 18.

The first round of the Havana talks, which have been held behind closed doors, are due to end on Thursday.