  Using the method of covariant symbols we compute the divergent part of the
effective action of the Proca field with non-minimal mass term. Specifically a
quantum Abelian vector field with a non-derivative coupling to an external
tensor field in curved spacetime in four dimensions is considered. Relatively
explicit expressions are obtained which are manifestly local but non polynomial
in the external fields. Our result is shown to reproduce existing ones in all
particular cases considered. Internal consistency with Weyl invariance is also
verified.
