Nonquasineutrality in perturbations has a destabilising influence on a plasma which is not in thermodynamic equilibrium and has a density gradient across a homogeneous axial magnetic field. This destabilising effect applies not only to short but also to long drift-dissipative instability waves. If long drift waves are excited, nonquasineutrality can also destabilise a plasma simultaneously with ion inertia. In strong magnetic fields the absence of quasineutrality of perturbations is important even when the density of charged particles is high.