  We further develop a recently proposed new approach to the description of the
relativistic neutrino flavour $\nu_e^L \leftrightarrow \nu_{\mu}^L$, spin
$\nu_e^L \leftrightarrow \nu_{e}^R$ and spin-flavour $\nu_e^L \leftrightarrow
\nu_{\mu}^R$ oscillations in a constant magnetic field that is based on the use
of the exact neutrino stationary states in the magnetic field. The neutrino
flavour, spin and spin-flavour oscillations probabilities are calculated
accounting for the whole set of possible conversions between four neutrino
states. In general, the obtained expressions for the neutrino oscillations
probabilities exhibit new inherent features in the oscillation patterns. It is
shown, in particular, that: 1) in the presence of the transversal magnetic
field for a given choice of parameters (the energy and magnetic moments of
neutrinos and the strength of the magnetic field) the amplitude of the flavour
oscillations $\nu_e^L \leftrightarrow \nu_{\mu}^L$ at the vacuum frequency is
modulated by the magnetic field frequency, 2) the neutrino spin oscillation
probability (without change of the neutrino flavour) exhibits the dependence on
the mass square difference $\Delta m^2$.
