by catastrophic Compton cooling and only under extreme conditions can it lead to relativistic bulk velocities." This conclusion was also confirmed by [@MeliaK-89] in their study of radiation-drag deceleration of very fast outflows. Then [@VokrouhlickyK-91] considered the motion of test particles moving along the symmetry axis of the Schwarzschild or Kerr space-times under the influence of radiation from a thin test disc determined by the Novikov-Thorne model. They propagated the radiation predicted by this model to the location of the particle and there integrated over the latter’s local sky, taking into account all the effects of general relativity resulting from the curvature of space induced by a central black hole. The energy-momentum tensor obtained in this manner was then projected onto the particle’s four-velocity in order to find the force which the radiation exerts on the particle. The authors concluded that the general relativistic effects on the radiation field (redshift, ray bending, dragging) do not affect the terminal speed of the particle significantly and also did not observe any significant effect of radiation on the axial pre-collimation of particles launched from the surface of the disc. They noticed, however, that the results did depend strongly on the luminosity profile of 