The low-momentum interaction Vlow-k derived from realistic models of the nucleon-nucleon interaction is presented in a separable form. This separable force is supported by a contact interaction to achieve the saturation properties of symmetric nuclear matter. Bulk properties of nuclear matter and finite nuclei are investigated for the separable form of Vlow-k and two different parametrizations of the contact term. The accuracy of the separable force in Hartree-Fock calculations with respect to the original interaction Vlow-k is discussed. For a cutoff parameter Λ of 2  fm-1, a representation by a rank-2 separable force yields sufficient accuracy, while higher ranks are required for larger cutoff parameters. The resulting separable force is parametrized in a simple way to allow for an easy application in other nuclear structure calculations.