The regions of high excitation gas detected around various Active Galactic Nuclei (AGN) are examined. The radiation emitted by the nucleus may be responsible for the high ionization of the line emitting gas. Evidence that the radiation field is anisotropic and collimated in a direction close to the cone axis is found. The possibility that a geometrically thick accretion disk is the source of the ionizing continuum is considered. Theoretical predictions and observational data are compared. The energetics requirements and the spatial distribution of the extended emitting gas for Seyfert and radio galaxies are analyzed.