  Long baseline radio interferometers can provide some interesting
opportunities for future SETI searches. Known advantages (compared to single
dishes or beam-formed arrays), include the large reduction in false-positives
due to the interferometer's natural suppression of RFI. This paper presents
other advantages - the presence of multiple interferometer baselines in an
array provide an important level of redundancy and additional confidence
(verification) in the detection of faint and potentially transient signals. The
SETI requirement for high time and frequency resolution is well matched to
wide-field VLBI techniques that permits the simultaneous analysis of thousands
of potential SETI targets within the field-of-view. Searching for a SETI signal
in the image plane has the important advantage that the signal location on the
sky is likely to be invariant on short timescales - this is a useful constraint
when potentially almost everything else could be changing (eg frequency drift
due to Doppler accelerations). Using archive data, we demonstrate how VLBI can
be used to conduct SETI searches. We target two targets within the field of
view - a galactic star and a galaxy at a redshift of 0.14. We place coarse
upper limits on any SETI signals from the two SETI targets, and note that while
the EIRP associated with the galaxy is comparable to the energy resources of a
Kardashev Type 2 civilisation, a distributed array of coherent transmitters
with excellent forward gain, could reduce this to more modest levels. We
therefore argue that targeted observations of extragalactic sources may also be
merited by interferometer surveys. Using VLBI to study the precise location and
motion of confirmed SETI signals is also discussed.
