  We exploit XMM-Newton archival data in a study of the extended X-ray emission
emanating from the Galactic Centre (GC) region. EPIC-pn and EPIC-MOS
observations, with a total exposure approaching 0.5 and 1 Ms respectively, were
used to create mosaiced images of a 100 pc x 100 pc region centred on Sgr A* in
four bands covering the 2-10 keV energy range. We have also constructed a set
of narrow-band images corresponding to the neutral iron fluorescence line at
6.4 keV and the K-shell lines at 6.7 keV and 6.9 keV from helium-like and
hydrogenic iron. We use a combination of spatial and spectral information to
decompose the GC emission into three distinct components. These comprise: the
emission from hard X-ray emitting unresolved point sources; the reflected
continuum and fluorescent line emission from dense molecular material; and the
soft diffuse emission from thermal plasma in the temperature range, kT ~
0.8-1.5 keV.
  We show that the unresolved-source component accounts for the bulk of the
6.7-keV and 6.9-keV line emission. We fit the observed X-ray surface brightness
distribution with an empirical 2-d model, which we then compare with a 3-d
mass-model prediction for the old stellar population in the GC. The X-ray
surface brightness falls-off more rapidly with angular offset from Sgr A* than
predicted. One interpretation is that the 2-10 keV X-ray emissivity increases
from 5 x 10^27 erg s^-1 Msun^-1 at 20' up to almost twice this value at 2'.
Alternatively, some refinement of the mass model may be required.
  The unresolved hard X-ray emitting source population, on the basis of
spectral comparisons, is most likely dominated by magnetic CVs. We use the
X-ray observations to set constraints on the number density of such sources.
Our analysis does not support the conjecture that a significant fraction of the
hard X-ray emission from the GC originates in very-hot diffuse thermal plasma.
