  Recently, Banados, Silk and West analyzed a collision of two particles near
the horizon of the extremal Kerr black hole and demonstrated that the energy in
the center-of-mass frame can be arbitrarily large provided the angular momentum
of one of the colliding particles takes a special value. As is known, the
vicinity of the extremal Kerr black hole horizon can be viewed as a complete
vacuum spacetime in its own right. In this work, we consider a collision of two
neutral particles within the context of the near horizon extremal Kerr geometry
and demonstrate that the energy in the center-of-mass frame is finite for any
admissible value of the particle parameters. An explanation of why the two
approaches disagree on the Banados-Silk-West effect is given.
