Abstract: A gas burner has a body, a supply unit and a lid having a central flame crown and a peripheral flame crown. The supply unit has at least one supply duct, three injectors connected to said at least one supply duct, three Venturi tubes respectively associated with said injectors, wherein the injectors and the Venturi tubes have parallel horizontal axes and fixing means used to fix the Venturi tubes in position. The body of the burner has a central chamber and two peripheral chambers in communication with the Venturi tubes and with an upper central chamber and an upper peripheral chamber respectively disposed under the central flame crown and the peripheral flame crown.