The hostage release could take two days , Cordoba said . NEW : A mediator says the rebel group will begin releasing 10 hostages Monday . The rebels have been holding a number of foreign journalists since last week in exchange for their release from captivity. The defense member calls the operation `` one of the greatest blows '' against the rebels . A top leader of one faction of the Revolutionary Armed Forces of Colombia is captured , he says .
NEW : A mediator says the rebel group will begin releasing 10 hostages Monday . The rebels have been holding a number of foreign journalists since last week in exchange for their release from captivity. The defense member calls the operation `` one of the greatest blows '' against the rebels . A top leader of one faction of the Revolutionary Armed Forces of Colombia is captured , he says .