  We study collision of particles in the vicinity of a horizon of a weakly
magnetized non-rotating black hole. In the presence of the magnetic field
innermost stable circular orbits (ISCO) of charged particles can be located
close to the horizon. We demonstrate that for a collision of two particles, one
of which is charged and revolving at ISCO and the other is neutral and falling
from infinity, the maximal collision energy can be high in the limit of strong
magnetic field. This effect has some similarity with the recently discussed
effect of high center-of-mass energy for collision of particles in extremely
rotating black holes. We also demonstrate that for `realistic' astrophysical
black holes their ability to play the role of `accelerators' is in fact quite
restricted.
