  The principal group of a Klein geometry has canonical left action on the
homogeneous space of the geometry and this action induces action on the spaces
of sections of vector bundles over the homogeneous space. This paper is about
construction of differential operators invariant with respect to the induced
action of the principal group of a particular type of parabolic geometry. These
operators form sequences which are related to the minimal resolutions of the
k-Dirac operators studied in Clifford analysis.
