  We present spectral measurements made in the soft (20-100 keV) gamma-ray band
of the region containing the composite supernova remnant G11.2-0.3 and its
associated pulsar PSR J1811-1925. Analysis of INTEGRAL/IBIS data allows
characterisation of the system above 10 keV. The IBIS spectrum is best fitted
by a power law having photon index of 1.8^{+0.4}_{-0.3} and a 20-100 keV flux
of 1.5E{-11} erg/cm^2/s. Analysis of archival Chandra data over different
energy bands rules out the supernova shell as the site of the soft gamma-ray
emission while broad band (1-200 keV) spectral analysis strongly indicates that
the INTEGRAL/IBIS photons originate in the central zone of the system which
contains both the pulsar and its nebula. The composite X-ray and soft gamma-ray
spectrum indicates that the pulsar provides around half of the emission seen in
the soft gamma-ray domain; its spectrum is hard with no sign of a cut off up to
at least 80 keV. The other half of the emission above 10 keV comes from the
PWN; with a power law slope of 1.7 its spectrum is softer than that of the
pulsar. From the IBIS/ISGRI mosaics we are able to derive 2 sigma upper limits
for the 20-100 keV flux from the location of the nearby TeV source HESS
J1809-193 to be 4.8E{-12} erg/cm^2/s. We have also examined the likelihood of
an association between PSR J1811-1925 and HESS J1809-193. Although PSR
J1811-1925 is the most energetic pulsar in the region, the only one detected
above 10 keV and thus a possible source of energy to fuel the TeV fluxes, there
is no morphological evidence to support this pairing, making it an unlikely
counterpart.
