  Spontaneous breaking of Lorentz invariance compatible with observational
limits may realistically take place in the context of string theories, possibly
endowing the photon with a mass. In this process the conformal symmetry of the
electromagnetic action is broken allowing for the possibility of generating
large scale ($\sim Mpc$) magnetic fields within inflationary scenarios. We show
that for reheating temperatures safe from the point of view of the gravitino
and moduli problem, $T_{RH} \laq 10^{9} GeV$ for $m_{3/2} \approx 1 TeV$, the
strength of the generated seed fields is, in our mechanism, consistent with
amplification by the galactic dynamo processes and can be even as large as to
explain the observed galactic magnetic fields through the collapse of
protogalactic clouds.
