  We report the discovery of a soft gamma ray source, namely IGR J18135-1751,
detected with the IBIS imager on board the INTEGRAL satellite. The source is
persistent and has a 20-100 keV luminosity of $\sim$5.7 $\times$ 10$^{34}$ erg
s$^{-1}$ (assuming a distance of 4kpc). This source is coincident with one of
the eight unidentified objects recently reported by the HESS collaboration as
part of the first TeV survey of the inner part of the Galaxy. Two of these new
sources found along the Galactic plane, HESS J1813-178 and HESS J1614-518, have
no obvious lower energy counterpart, a fact that motivated the suggestion that
they might be dark cosmic ray accelerators. HESS J1813-178 has a strongly
absorbed X-ray counterpart, the ASCA source AGPS273.4-17.8, showing a power law
spectrum with photon index $\sim$ 1.8 and a total (galactic plus intrinsic)
absorption corresponding to N$_H$ $\sim$5 $\times$ 10$^{22}$ cm$^{-2}$. We
hypothesize that the source is a pulsar wind nebula embedded in its supernova
remnant. The lack of X/gamma-ray variability, the radio morphology and the ASCA
spectrum are all compatible with this interpretation. In any case we rule out
the hypothesis that HESS J1813-178 belongs to a new class of TeV objects or
that it is a cosmic "dark particle" accelerator.
