  We present a new method of constraining the mass and velocity anisotropy
profiles of galaxy clusters from kinematic data. The method is based on a model
of the phase space density which allows the anisotropy to vary with radius
between two asymptotic values. The characteristic scale of transition between
these asymptotes is fixed and tuned to a typical anisotropy profile resulting
from cosmological simulations. The model is parametrized by two values of
anisotropy, at the centre of the cluster and at infinity, and two parameters of
the NFW density profile, the scale radius and the scale mass. In order to test
the performance of the method in reconstructing the true cluster parameters we
analyze mock kinematic data for 20 relaxed galaxy clusters generated from a
cosmological simulation of the standard LCDM model. We use Bayesian methods of
inference and the analysis is carried out following the Markov Chain Monte
Carlo approach. The parameters of the mass profile are reproduced quite well,
but we note that the mass is typically underestimated by 15 percent, probably
due to the presence of small velocity substructures. The constraints on the
anisotropy profile for a single cluster are in general barely conclusive.
Although the central asymptotic value is determined accurately, the outer one
is subject to significant systematic errors caused by substructures at large
clustercentric distance. The anisotropy profile is much better constrained if
one performs joint analysis of at least a few clusters. In this case it is
possible to reproduce the radial variation of the anisotropy over two decades
in radius inside the virial sphere.
