  We investigate the conditions for radio emission in rotating and oscillating
magnetars, by focusing on the main physical processes determining the position
of their death-lines in the P-\dot{P} diagram, i.e. of those lines that
separate the regions where the neutron star may be radio-loud or radio-quiet.
After using the general relativistic expression for the electromagnetic scalar
potential in the magnetar magnetosphere, we find that larger compactness
parameters of the star as well as larger inclination angles between the
rotation axis and the magnetic moment produce death-lines well above the
majority of known magnetars. This is consistent with the observational evidence
of no regular radio emission from the magnetars in the frequency range typical
for the ordinary pulsars. On the contrary, when oscillations of the magnetar
are taken into account, the death-lines shift downward and the conditions
necessary for the generation of radio emission in the magnetosphere are met.
Present observations showing a close connection between the burst activity of
magnetars and the generation of the radio emission in the magnetar
magnetosphere are naturally accounted for within our interpretation.
