  If the stability of the dark matter (DM) particle is due to an accidental
symmetry, nothing prevents UV physics from destabilising it by inducing DM
decays suppressed by powers of the UV scale. The seesaw physics, presumably at
the origin of neutrino mass, could induce such a decay. We show that if the
seesaw scale lies around the usual Weinberg operator scale, the induced DM
decay could generically lead to neutrino lines whose intensity is of the order
of the present sensitivity of neutrino telescopes. We illustrate this
possibility with models in which the DM is made of the gauge boson(s) of an
abelian or non-abelian gauge symmetry.
