We study inverse scattering problems at a fixed energy for radial Schrödinger operators on R n , n ≥ 2. First, we consider the class A of potentials q(r) which can be extended analytically in. If q andq are two such potentials and if the corresponding phase shifts δ l andδ l are super-exponentially close, then q =q. Secondly, we study the class of potentials q(r) which can be split into q(r) = q1(r) + q2(r) such that q1(r) has compact support and q2(r) ∈ A. If q andq are two such potentials, we show that for any fixed a > 0,when l → +∞ if and only if q(r) =q(r) for almost all r ≥ a. The proofs are close in spirit with the celebrated Borg-Marchenko uniqueness theorem, and rely heavily on the localization of the Regge poles that could be defined as the resonances in the complexified angular momentum plane. We show that for a non-zero super-exponentially decreasing potential, the number of Regge poles is always infinite and moreover, the Regge poles are not contained in any vertical strip in the right-half plane. For potentials with compact support, we are able to give explicitly their asymptotics. At last, for potentials which can be extended analytically in ℜz ≥ 0 with | q(z) |≤ C (1+ | z |) −ρ , ρ > 1 , we show that the Regge poles are confined in a vertical strip in the complex plane.