The BBC said the U.N.'s FM frequency has been jammed since the crisis began but the broadcasts continued on unofficial frequencies.
Gbagbo has control of state television, Radio Television Ivorienne, which is a land-based broadcaster.
Ouattara has set up another land-based station and it broadcasts to Abidjan, where he remains in a hotel protected by U.N. peacekeepers.
November's election was intended to reunify the country, which was divided between the north and south after a conflict in 2002.
Gbagbo said the United Nations and the international community, most of which recognizes Ouattara as the winner of the election, is biased against him.