  The flavour singlet axial Ward identity with Osterwalder-Seiler twisted mass
Wilson fermion action is studied on a finite lattice, with finite fermion mass
and the Wilson parameter r up to 1. Approach to the infinite volume chiral
limit and emergence of the anomaly is significantly better than that obtained
with O(a) and O(a^2) improved fermion actions. We have shown explicitly that up
to O(g^2), parity violating terms cancel in the Ward identity even at finite
volume and finite lattice spacing.
