President Hugo Chavez said Saturday that the leader of Colombia's largest rebel group has contacted him as the Venezuelan leader seeks to mediate between the leftist guerrillas and Colombia's U.S.-allied government.

Chavez said he received a letter from Manuel Marulanda, commander of the Revolutionary Armed Forces of Colombia, or the FARC, but did not reveal its contents.

Venezuela's socialist president described lengthy talks Friday night with Colombian peace commissioner Luis Carlos Restrepo that are part of Chavez's attempt to broker an exchange of rebel-held hostages for imprisoned guerrilla fighters.

"I received a letter from Marulanda, commander of the FARC, several days ago, and last night we were evaluating positions," Chavez said.

Chavez has said he expects to meet soon with a high-ranking representative of the FARC to arrange a possible exchange of hundreds of imprisoned guerrillas for about 45 prominent rebel-held hostages. Among those being held by the rebels are three U.S. defense contractors and former presidential candidate Ingrid Betancourt, a French-Colombian citizen.

The Colombian government and the FARC have voiced support in principle for the swap but have long argued about how to achieve it.

"If I have to go to the gates of hell to try for a humanitarian accord -- and beyond that a peace accord in the beloved sister nation of Colombia -- well I will go there with your approval," Chavez told supporters during a televised speech in Caracas.

Chavez is for the first time stepping squarely into Colombia's long-running conflict as a facilitator, a role the Colombian government invited him to play.

"I started off accepting the role of observer but not anymore -- I've fallen into the role of mediator," Chavez said Saturday.