  For an integrable Hamiltonian system we construct a representation of the
phase space symmetry algebra over the space of functions on a Lagrangian
manifold. The representation is a result of the canonical quantization of the
integrable system in terms of separation variables. The variables are chosen in
such way that a half of them parameterizes the Lagrangian manifold, which
coincides with the Liouville torus of the integrable system. The obtained
representation is indecomposable and non-exponentiated.
