  We study neutrino spin oscillations in background matter under the influence
of strong electromagnetic and gravitational fields. The neutrino spin evolution
is treated quasiclassically. We derive the effective Hamiltonian governing spin
oscillations of a neutrino moving in the vicinity of a black hole and
interacting with a relativistic magnetized accretion disk around a black hole.
Applications for the studies of spin oscillations of astrophysical neutrinos
are considered.
