  In the inverse seesaw extension of the standard model, supersymmetric or
non-supersymmetric, while the light left-handed neutrinos are Majorana, the
heavy right-handed neutrinos are pseudo-Dirac fermions. We show how one of
these latter category of particles can contribute quite significantly to
neutrinoless double beta decay. The neutrino virtuality momentum is found to
play a crucial role in the non-standard contributions leading to the prediction
of the pseudo-Dirac fermion mass in the range of $120\, {MeV}-500\, {MeV}$.
When the Dirac neutrino mass matrix in the inverse seesaw formula is similar to
the up-quark mass matrix, characteristic of high scale quark-lepton symmetric
origin, the predicted branching ratios for lepton flavor violating decays are
also found to be closer to the accessible range of ongoing experiments.
