  JHKL'M (1-5 micron) imaging of a sample of Seyfert (Sy) 2 galaxies is
presented. We confirm that the 1-2.2 micron nuclear continuum of some Sy 2s is
dominated by stellar emission, whereas the continuum emission at longer
wavelengths (3-5 micron) is almost entirely non-stellar in origin. The IR
non-stellar spectral energy distributions (SED) (up to 15 micron) of Sy
galaxies show a variety of shapes, and they are well reproduced with the
tapered disk models of Efstathiou & Rowan-Robinson (1995). We have used two
models, one including an optically thin cone component and a coneless model.
Although our modelling of the SEDs does not allow us to favor either model to
account for all the observed SEDs, we find that the viewing angle towards the
central source is well constrained by both models. We have also investigated
non-stellar color-color diagrams. The colors of the Sy galaxies with viewing
angles theta < 30 degree are better reproduced with the cone model. These
diagrams provide a good means to separate Sy 2s with moderate obscuration (A_V
< 20 mag, from hard X-ray observations) from those with high obscuration. The
ground-based 4.8 micron and ISO 9.6 micron luminosities are well correlated
with the hard X-ray luminosities of Sy 1s and 2s. These continuum emissions
appear as a good indicator of the AGN luminosity, at least in the cases of hard
X-ray Compton-thin Sy galaxies. We finally stress the finding that some Compton
thick galaxies show bright non-stellar emission at 5 micron. This suggests that
the near-IR emission in Sys is produced in an extended component illuminated by
the central source, that is more visible from all viewing angles. We discuss
possible implications of mid-IR surveys for the search of counterparts of
highly obscured hard X-ray sources. (Abridged)
