  Scattering of particles in the gravitational field of rotating black holes is
considered. Expressions for scattering energy of particles in the centre of
mass system are obtained. It is shown that scattering energy of particles in
the centre of mass system can obtain very large values not only for extremal
black holes but also for nonextremal ones. It is shown that for realizing of
the collisions with infinite energy one needs the infinite interval not only of
the coordinate time but also the infinite interval of the proper time of the
free falling particle.
