Vertex cut sets

Most partitioning algorithms, for example spectral orderings, give edge
cut sets but what we often want (and indeed Jennifer Scott and I need
in a present study) is a vertex cut set.  Although getting such a set
is trivial, I believe that getting a low cardinality set is not ??

Does anyone have or know of a code (preferably Fortran :-)) for doing a
reasonable job on this.  We know there must be such algorithms buried within 
codes like MeTiS but there does not appear to be a separate interface for
this task.

Thank you for any help on this

Iain Duff