Colombia's Farc rebels say they will release four captive Colombian politicians, France's foreign minister Bernard Kouchner has said.
Mr Kouchner said he was happy with the announcement
That is one hostage more than the Farc announced last month. No date has been set for their release.
Mr Kouchner made the announcement after meeting Venezuela's President Hugo Chavez about efforts to secure the release of Farc hostages.
He is due to hold talks with Alvaro Uribe in Colombia later on Thursday.
Mr Kouchner said on Wednesday that the Venezuelan leader told him "there is a fourth hostage to be released, not just three".
The identity of the fourth hostage is not known, but Mr Kouchner said it would be a politician.
The Farc want to exchange hostages for prisoners
The Farc said in a statement on 31 January that it would free three hostages in return for mediation efforts made by Mr Chavez.
The hostages were named as former lawmakers Luis Eladio Perez, Gloria Polanco and Orlando Beltran.
Mr Kouchner's visit comes just ahead of the sixth anniversary of the capture of the French-Colombian politician, Ingrid Betancourt, on Saturday.
Mrs Betancourt is among about 40 high-profile captives held by the Farc, and was taken hostage whilst campaigning for the Colombian presidency in 2002.
Mr Chavez helped broker a deal to free two hostages last month, but he was removed as an official mediator by the Colombian government amid accusations that he favoured the rebels.
Mr Uribe has taken a firm line in negotiations with the Marxist rebels.