An illumination system (10) for spot illumination comprising a tubular reflector (2) with a reflective inner surface, the tubular reflector (2) having an entrance aperture (7) and an exit aperture (8) being larger than the entrance aperture (7); a light-source array (1) comprising a plurality of light-sources (13a-c; 30a-d, 31a-d, 32a-d) arranged to emit light into the tubular reflector (2) at the entrance aperture thereof; and a light-diffusing optical member (9) arranged to diffuse light emitted by the illumination system (10). The light-diffusing member (9) is configured to exhibit an increasing diffusing capability with increasing distance from an optic axis (12) of the illumination system.