  We report the discovery in the Galactic Centre region of two hard X-ray
sources, designated as XMM J174457-2850.3 and XMM J174544-2913.0, which
exhibited flux variations in the 2--10 keV band in excess of a factor of 100 in
observations spanning roughly a year. In both cases the observed hydrogen
column density is consistent with a location near to the Galactic Centre,
implying peak X-ray luminosities of ~5 x 10^34 erg/s. These objects may
represent a new population of transient source with very different properties
to the much more luminous Galactic Centre transients associated with neutron
star and black-hole binary systems. Spectral analysis shows that XMM
J174457-2850.3 has relatively weak iron-line emission set against a very hard
continuum. XMM J174544-2913.0, on the other hand, has an extremely strong
K-line from helium-like iron with an equivalent width of ~2.4keV. The nature of
the latter source is of particular interest. Does it represent an entirely new
class of object or does it correspond to a known class of source in a very
extreme configuration?
