  The effective interaction of a neutrino with a photon in magnetized plasma is
obtained from a strong field expansion in the electroweak standard model. The
interaction is expressed by a Chern-Simons form of the neutrino current and the
electromagnetic vector potential of the coupling strength proportional to
$\frac{n_e}{B} \times e G_F$. The derivation of the interaction Lagrangian and
its properties are presented.
