Abstract: The talk is about the simulation of recently discovered hard X-ray and gamma radiationsources localized near the top of solar flare loops. The calculations were performed in the context of a modelof a flare magnetic loop inhomogeneous with respect to the magnetic field. Two cases of injection were considered: isotropic and anisotropic along the loop axis. The distributions of electrons along the loop are foundby solving the non-stationary relativistic kinetic equation in the Fokker–Planck form. Based on the calculatedelectron distribution functions, the spatial brightness distribution of hard X-ray and gamma radiation hasbeen calculated. Radiation characteristics are compared for different sets of injection parameters. We also consider peculiarities of the directivity and polarization dynamics of hard X-rays and gamma-rays from different regions of a flare loop. The modeling results suggest that the degree of directivity and polarization and the variationof these parameters in time depend on the position within the loop and vary fundamentally between cases ofisotropic and anisotropic (longitudinal) injection of electrons. The revealed peculiarities of the directivity andpolarization dynamics may be used in X-ray and gamma-ray diagnostics of the type of pitch-angle distribution that characterizes the electrons accelerated in a certain specific observed flare.