BOGOTA -- The release of the captives Colombia's FARC rebels promised to free will take place Sunday, an opposition lawmaker who has acted as a mediator between the government and the guerrillas said.

"I already have the coordinates; the first release will be on Sunday," Sen. Piedad Cordoba told reporters at the end of a meeting with representatives of the International Committee of the Red Cross in Bogota.

She said the people who will make up the team receiving the hostages will travel this weekend to Brazil, which is providing logistical support for the humanitarian mission.

"The entire delegation will leave Brazil (for Colombia)," said Cordoba, to whom the FARC said they would deliver six of the 28 "high-value" hostages they intend to swap for hundreds of jailed guerrillas, including three already extradited to the United States.

The Revolutionary Armed Forces of Colombia, or FARC, announced five weeks ago its decision to unilaterally free former provincial Gov. Alan Jara, erstwhile legislator Sigifredo Lopez and four unnamed members of the security forces.

"The entire process is already underway," said Cordoba, whom the rebels have designated as leader of the delegation that is to receive the captives, with the ICRC also taking part in the expected handover.

Cordoba refrained from revealing the identities of the other people who will travel with her and the ICRC members to receive the hostages.

"We're still not going to give names, for the security of those who are going," she said. "There are too many threats."

The FARC, a Marxist rebel army that has fought a decades-old struggle against a succession of Colombian governments, holds some hostages for political leverage and others in hopes their family members will pay for their release.

The guerrillas' most famous captive had been former presidential candidate and dual French-Colombian citizen Ingrid Betancourt, but she and other hostages were rescued last year during an operation in which an elite group of Colombian army soldiers tricked the members of a FARC unit into thinking they were with the ICRC. EFE